# How to add tactics and maneuvering into space warfare

I have a setting with space fleets fighting, the include both capital ships and human flown 'space fighters', which I already put some work into justifying: How to keep humans pilots instead of AI in sci-fi future?

I want to encourage smart tactics, maneuvering, the equivalent of outflanking and surprising enemies etc to some degree within my world, particularly since my main focus is on a small group of folks flying powerful crafts, but who would ultimately need to use tactics to make the most of battles due to their small numbers.

The problem is that space is big and empty. Most tactics don't work well when you can't surprise anyone, and you don't have any terrain to exploit to gain an advantage. I'm looking for ideas to add variables which encourage more tactics and planning on the scale of one fleet engaging another (Larger strategic concerns are less in scope to my story, and also carry over better from current warfare to space warfare so it's easier to imagine them).

I'm open to modifying technology, weapons, and environment to a degree to create or encourage better use of tactics. However, I'm trying to stay somewhat hard sci-fi, it's okay to make up a technology that feels somewhat plausible, but full ramifications of such technology existing must be explored. I'd love general suggestions for making any space warfare more tactical, as well as specifics for my world.

As to my world, here is how the technology works, some of it already was altered to encourage or better use tactics but I still don't have enough of it:

The general world:

1. Travel is done at sub-light speeds except at specific points where one can open up jump point to another region, only larger ships have the power and equipment to make jumps usually. There are quite a few of these jumps between regions. I'm open to tweaking these and suspect tweaks to how jump points work is probably the easiest way to add more tactical options.
2. Limited faster than light communication exists. however, it is not entirely instantaneous and can only travel so far before the signal degrades. Most jump points also act as relays to strengthen and pass comms through, but obviously whoever owns a jump point can prevent relaying enemy comms. Messages can be sent without jump points but require more energy and suffer more lag. In combat FTL communication is less efficient due to weapons and jamming systems, only short data grams can get through and they may come in irregularly.
3. Geneva convention insists space battles must be held a certain minimum distance out from any inhabited planet or habitat to avoid stray bullets destroying all life on a planet. Battles for these locations occur, but generally far enough away from the actual planet that someone isn't going to be able to jump around a moon and surprise you
4. Space. Is. Big. While I've created systems to encourage closer range battles I plan to stay accurate in regards to the size of space, and the limited rate of sublight engines producing acceleration compared to the size of space. In short, hiding behind a moon and jumping out of nowhere isn't as effective when it takes over an hour of acceleration to even begin to move around the moon to surprise someone...

Enemy crafts and shield technology.

1. Shield technology exists and is used on all capital ships, but most smaller crafts are not shielded and easily destroyed. Shields are best destroyed with certain types of energy weapons that have rather short ranges, encouraging battles at 'close' range, from an astrological standpoint.

2. The efficiency of shields means just throwing more energy at them is a bad way of destroying them, instead, all weapons and tactics for taking out capital ships are focused on intentionally ruining the resonance of the shields, which causes destructive interference and drains the shields energy reserves. As long as a shield knows what attack to expect it can be calibrated to be very effective against it, however, it can't be perfectly calibrated against all types of attacks at once, and if poorly calibrated for an attack the shields will lose power with an inefficient deflection...

3. A combination of a few strong attacks with lots of weak attacks tends to be a very effective way of draining shields because the way to configure against lots of weak attacks is very different from defending against a strong attack. For this reason, all capital ships carry a number of smaller fighters and bomber crafts. Bombers swarm shields and attack from all sides while capital ships hit with one large energy weapon, the combination draining the shields far better than either tactic alone; fighters simply protect bombers and destroy enemy bombers.

4. To squeeze efficiency out of shields they are calibrated for the anticipated fight when they are brought up, and then they slowly adjust their calibration during the fight (Once shields are turned on the calibration must be slowly shifted to a new one, quick changing of celebration while shields are active will waste a large amount of energy). For instance, if two capital ships are fighting the shields will be calibrated for one capital ship hitting from the port side and a few dozen bombers attacking from multiple angles. As bombers are destroyed the shields recalibrate to focus on being more efficient at defending against the capital ships weapons at the expense of being worse against bombers, as there are fewer bombers to defend against. Likewise, as the enemy capital ship moves the shields will recalibrate to keep the shields strongest in the areas the capital ship could hit with its beam weapon.

5. capital ships tend to have only one, or at most two, beam weapons, and very little in way of point defenses against bombers; it's difficult to fire through your own shields and limiting the number of places you're firing through allows shields to be calibrated to higher efficiency. Beam weapons grow weaker with distance and thus can grow increasingly devastating as capital ships close; not that closing on an enemy ship is always the best way of engaging them.

Obviously, shields have been modified intentionally so that sneak attacks and baiting the enemy into starting with a shield that is poorly calibrated for a fight is a good way to get an upper hand. The problem is that the idea of 'sneak attacks' is kind of hard in space. The enemy can pretty well anticipate exactly what you're throwing at them and where since they see you coming hours or days before you arrive, and there are limited ways to surprise them or maneuver differently since your maneuver speeds are so limited.

• This may be helpful. worldbuilding.stackexchange.com/questions/9717/… – James Nov 19 '15 at 19:19
• Have you tried approaching your space fight as information warfare? Many tactics which are interesting in ground combat or air combat rely on the fact that you cannot know everything about what your opponent is doing, and they cannot know everything you are doing. This lets you explore a part of warfare which looks like a poker game, or a similar partial-information game. If you can find a way to make that game interesting, there's a decent chance you can map it to warfare to make warfare appear interesting. – Cort Ammon Nov 19 '15 at 23:37
• the book Ender's Game has a lot of interesting content you might find useful. – enderland Nov 20 '15 at 13:53
• I also recommend Larry Niven's Protector for a scientifically based space battle. – Todd Wilcox Nov 20 '15 at 15:50
• @dsollen More along the lines of build a bunch of cheap ships that are little more than empty hulls the same weight as a regular destroyer or what-not. In the middle of a pitched battle aim a bunch of them at the enemy capital ship and drive them forward as fast as possible. Even if they get "destroyed" the resulting debris cloud, heading at high speed towards the ship, will drain the enemy's shields or force them to calibrate them for the debris, rather than weapons fire. Plus these ships should be much cheaper than real ships, that need weapons and crews. – Marshall Tigerus Jun 29 '16 at 18:30

## 19 Answers

I think your setting and tech descriptions create some good opportunities for interesting tactics.

With only a single protagonist ship, sublight maneuver itself may not seem so interesting, but there can still be some interesting tactics available even for approaching an enemy, such as:

Pretend to be a friend. If the protagonist ship can emulate a friend or non-enemy, they could get within a range where they could take advantage of surprise. Ways to emulate a non-enemy could involve either being originally externally the same as one's enemies, i.e. if the ship is of the same construction, or intentionally built that way, or is a captured ship. Or they could have developed technology which involves adding a shell to the ship surface that acts as a ship costume or electronic projectors which just present an image that is the same from a distance.

You already have powerful complex tunable shield technology. It seems to me that this technology might also be able to project an image that makes a ship look like a different ship of a similar size.

If one can somehow appear to be a friendly ship, then a successful ambush/impersonation requires defeating the identification protocols, which probably requires impersonating enemy officers, and/or forcing them to act as if they were confirming their approach. They could either be actually captured or perhaps "captured" by recording their actual communications in the past and then using those recordings. This tactic would also require not raising an alarm, and not seeming to be in the wrong place at the wrong time, which might or might not be very hard or nearly impossible, depending on the scenario. It would probably be far easier to impersonate 3rd parties rather than a ship from the same fleet as the target, unless you've actually captured such a ship without letting the enemy know you have.

If there are huge cargo transports in the setting, a capital ship might be able to hide inside of one. Then it will appear to be a cargo transport because it is - it just has a capital ship inside. If there is a lot of mass cargo transport in the setting, this may make stealth by impersonation quite possible, to the extent that you can capture such ships and engineer the insertion and the breakout.

Another technology that might enable stealth and ambush could be something like a redeployable concealment cloud. Perhaps a system of devices could deploy a cloud of magnetic dust or gas around a ship, which prevents seeing what's inside it. Magnetic so it can be kept in a bubble around the ship, and retracted and re-used. If this was a common and routinely-used system, then again, they might see something coming but not know what it is, and that might not raise an alarm if the setting includes many different types of ships using such systems as a known common practice - suddenly it becomes possible to hide by being one of many anonymous clouds moving about. A decoy could also deploy a cloud.

Decoys in general, whatever the technology that allows them to look like your ship, meaning that you can have a shell-game maneuver situation.

Even without decoys, but especially with them, if sub-light propulsion involves standard inertia and fuel, then inertial maneuver can itself be an interesting tactical proposition, though it will be more complex the more objects are in space. If it was just two ships with beam weapons, not so much, but missiles and fighters and warp points and decoys are all moving objects with inertia and facing directions in three dimensions and limited fuel and changing mass if they use reaction mass, so there can be many different guessing games there about how to deploy to try to get the enemy to commit to a deployment that you can use to get yourself into advantageous situations, which as in almost any tactical situation (whether real-world naval or martial arts) can involve out-anticipating the opponent's thinking and movements, so they do something which you can respond to in a way that leads to your advantage and so a successful outcome. What helps that a lot is when the opponent has inaccurate information about your plans, deployment, and/or capabilities. You've read Honorverse books, so you've seen a lot of variations on that. Weber (the author of that series) is a game designer, and no doubt plots out his situations, runs the math, and re-plays various scenarios until he finds something he thinks is interesting to write about.

Your slowly-adapting shield systems add yet another dimension to that, because they have their own spatial orientation and settings which take significant time to change. If the protagonist ship shield has some unexpected abilities, even just speed or directions in which it can adjust, raise, lower, or spoof its settings, then that can provide another way (and another spatial/directional component) with which to outmaneuver an enemy. For instance, once close enough to an enemy, you might be able to maneuver past / around it more quickly than it can keep its shield strength concentration facing you, but if your shields can be ready to redeploy that way, then you could get a decisive shield advantage by quickly changing direction at close range in a way they can't respond to but you can... if the range and rotation and shield adjustment speeds are within certain values, anyway. There are also axes of "maneuver" provided by different attack types, and the mechanics you mentioned of tuning shields to allow weapons fire through.

And of course, your whole fighter/bomber/low-PD situation also lends itself to maneuver and tactics. Clearly the main avenue is you tune your shields to defensive mode, then have your fighters take care of their fighters and bombers, and once their fighters are handled, have your bombers destabilize the enemy shields by hitting them from different directions with different attack settings, and then switch capital shield configuration to offense, and plaster the enemy shield, or even compel them to surrender since they should be able to see the hopelessness of their situation before they're destroyed, since their shields take some time to wear down and they can see what's going on.

Another weapon system that might make sense would be some sort of shrapnel bomb. If your fighters get outmatched, tell your fighters which side of your capital shields to shelter behind and then roll a few bombs out, which explode and send fighter-threatening debris everywhere, hopefully, evening the odds.

The FTL warp point system, of course, offers many opportunities for tactics, depending on how they work, exactly, and how they are laid out, etc. It also provides a means for technological maneuver advantages for your protagonists, as well as a potential advantage for the lone wolf, if the opponents have to spread out to protect many points and can't cover them all. It gives you a lot of leeway to design something that has room for interesting maneuvers and tactics. For examples:

• Maybe warp points allow warping within a generous radius of the point, but there are trade-offs in terms of energy used, velocity going in/out, time required, accuracy, risks, ability to track where someone went or came from, or whatever, which can be mitigated by different qualities and/or settings of technology.

• Perhaps the distance or even shape of a warp field determine how much energy and time is required to prepare, align and recover from a warp in or out, as well as the required entry velocity, and resulting exit velocity.

• If warping requires a large energy build-up and expenditure, and/or electronic disruption, there may be trade-offs, possibly modified by the conditions as above as well as technological attributes, which may be in conflict with getting those complex shields working efficiently, just because of the power use, or possibly other effects (e.g. your shield matrix needs to be cooled and/or de-Gaussed after a warp or something). Thus ships could be vulnerable before and/or after jumps, providing a window of opportunity needing to be covered by other ships or fighters to reduce risk at either or both ends of a jump.

• The arrival of an incoming warp might also (or even only) disrupt or even displace nearby ships, shields, signals and/or electronics, or have other effects, which would have to be taken into account for both defensive and offensive tactics. There might be simple or different effects around where a ship warps away. This could make it hard to defend a warp point, or at least provide some time to maneuver and prepare before an attack via warp.

• If warp points do need ships to be in a very specific place with a specific velocity when they warp in or out, that, of course, can be taken into account in tactics. Some automated defenses, mines or obstacles might be used, as well as pre-targeted weapons aimed at the point.

• Maybe there's a way to disrupt a warp point. What if you get the enemy armada to chase you and track you to a certain warp point, but you've left something there that will throw off the jump (maybe a big asteroid does the trick)? For example, you might be able to get a large number of enemies scattered to the four winds, buying you time and getting the enemy ships still near warp points to try to redeploy to recover the remaining points while the rest of the fleet tries to make its way back to warp-connected space.

• Another elaborate ruse could involve capturing a command communication warp point hub, and making them give out a pre-designed series of false orders, including that an enemy communications disruption attack is expected, and then doing something that disrupts the whole warp communication network. Then you have until they make sense of that to do whatever your real objective is.

• A warp point system could also involve moving via a kind of hyperspace. Without a warp point, you can't travel long-distance (or not reliably), but ships might still be able to enter hyperspace without a warp point. If so, that means they may be able to effectively hide/cloak, and it also means that conditions in hyperspace may be different than normal space, and allow you to define conditions the way you want them to be for technology and resulting tactics. Shifting in and out of hyperspace might be a standard military technique. Or it might not have been because of technical disadvantages, but your protagonists' technological advantage might be that they have a new technique or technology which allows them to have a great advantage while doing so, letting them not only hide but also gain tactical and/or combat advantages such as short hops to flank, quick range changes, or getting the enemy into hyper where you have some technological advantages.

All of the above could provide all sorts of situations for out-guessing where and when ships would warp in and out, as well as tactics for having ships hop in, see what's there, and hop out, having the defenders decide whether or not to try to follow, or to call in reinforcements when or after a delay after someone pops in, or to retreat until enough force can be mustered, based on estimates of enemy fleet size. If warping causes disruption, this will be taken into account and used for tactics.

• many great answers thank you. Some aren't viable simply due to nuances of the story or where I want to focus it; but some are useful for me, and some I think can be tweaked to work in ways that will prove advantageous. however, most important, you answered MY question, with consideration to my world; even reading my comments on other questions first, which shows extra though put in fitting answer to question. That fact is what elevated you to getting selected as top answer :) – dsollen Nov 23 '15 at 15:16
• On the clouds, mixing in diamond particles would reduce the effectiveness of laser weapons. – Mormacil Apr 9 '17 at 9:43

As you say, space is pretty empty. For most battles, all that's going to make up the battlefield are the ships. But I say you can use this to great effect.

1. Shadows: enemies can't see your ship if you're behind another ship. When you've got capital ships involved, you can probably hide dozens or even hundreds of your fighters from the enemy until you decide it's time to attack. Plus, when attacking, you can never know what you'll find behind the enemy's capital ships. Keep in mind that even though ships are going to be really far apart most of the time, that just means everyone's shadows will be very large by the time you get out to the distance where they'll be used.

2. Blind spots: Your ships probably aren't going to be spheres covered on all angles with guns. Much like seafaring warships (or even airships like the AC-130), most of their guns should be centered on one or two sides, so they can hit a single enemy formation with everything they've got at once. With this in mind, there will always be places you don't want to be in reference to an enemy ship, and places you want the enemy ships to be in reference to you. With many ships and in three dimensions, these calculations could get very difficult, so a lot of inexperienced pilots are going to fly right into the killzone, but a good pilot may be able to navigate the battlefield, avoiding these 'invisible' obstacles and leading the enemy straight into them.

3. Time. This is probably one of the coolest things about space battles, the fact that so many systems are going to be constrained by the speed of light, and so many more are going to have to wait a long time to see results. A lot of what your pilots do will depend on assumptions about what's coming, and unexpected moves will be more devastating simply because it'll take longer to realize what's happened.

What this amounts to is a lot less looking and a lot more thinking. Pilots will have to intuitively understand the positions, orientations, and intentions of both their own forces and the enemy. There may not be cover, but by taking advantage of the points I've described above, pilots should be able to keep themselves out of the worst of the enemy's fire, and force the enemy to do the opposite. The geography of the battlefield will be comprised of its combatants; the 'high ground' will be having the best angles on the enemy, while a 'cornered' enemy is one that cannot move without entering the line of fire. As ships move, the terrain will constantly shift, which, at least to me, sounds like a great catalyst for some exciting battles.

• I do really love this answer, mostly because it brought up new points to me. Admittedly 3 is not as bad due to the (relatively) close range of battles and limited FTL options. I like 1 point though. I had already thought of the fact that you can't anticipate how many fighters are docked in capital ships being an advantage (given my heroes fly Aces, expensive craft barely larger then a fighter that are shielded and as dangerous as some capital ships, finding a small ship with a hanger with 5 Aces is going to really ruin what looked like an easy fight). However, using shadows is a new idea. – dsollen Nov 19 '15 at 19:57
• sadly only the 'enemy' sides can really use blind spots, my heros have only one capital ship to their side. Still, I want to show some every side having some smarts, so this is still a good option to have. – dsollen Nov 19 '15 at 20:00
• @dsollen Where it gets interesting is when you combine #1 and #2, and use one enemy's shadow to create another enemy's blind spot. With some good maneuvering, you can minimize the enemy's field of view simply by forcing them into each other's way. – DaaaahWhoosh Nov 19 '15 at 20:08
• You could always have a giant, mirror-like reflective box ship that contains your whole fleet then have the fleet either leave from the rear or suddenly drop all sides (of the box) and have a full scale surprise attack in an instant. That way you would not have the restriction of energy (for stealth shields) and could even fire a full fleet barrage through the "box" itself before the full size of the fleet could be ascertained by the enemy. – The Wandering Coder Nov 20 '15 at 2:24
• Real space battles will involve an awful lot of waiting time as you get ships into position... shoot once or twice, then wait to get into position again. In the real-life, space ships can't reverse orbit on a dime (because they're travelling thousands of meters per second in orbit), etc... – SnakeDoc Nov 20 '15 at 17:34

First I’d recommend looking to the Honor Harrington series. https://en.wikipedia.org/wiki/Honorverse They do the best job of accurately representing space combat from all the sci-phy I have read.

Some things stolen from there. Its hard to pin down forces that don’t want to fight unless they have to defend the location. (Planet/shipyard/starbase) Stealth technology vs speed. If you can stealth your ship you can still ambush. Being able to maneuver while stealthed increases the ambush range. Even though space is huge, there are still ideal places to enter and leave a system so you can predict movments and where to set up an ambush. Space is big. Even though you might be able to detect a ship, do you have the resources to look at every place in a star system it could be?

• Yes I have read it, and your right about all you said. Though..hmm I'm not sure I want to encourage stealth technology to the level that it exists in the Honor verse. It would keep my main characters a little too slow to do anything (so much time waiting to drift somewhere), and potentially slow down the action by making it a little too tactical. It's still a good point though. I may play with some way to incorporate some of 'stealth' tricks while limiting them enough that they don't take over all of combat. – dsollen Nov 19 '15 at 18:50
• I'm thinking maybe if someone can detect the action of a jump point from a distance so they know something is incoming but not necessarily the number and quantities it would still allow setting up some surprise tactics around gates using powered down ships. The fact that my shields have invalidated 'stealth missile' tricks. Big problem I have is justifying speeds. Really the speed of delta V of ships is so limited by G force it means any ship suddenly powering up to attack will take forever to reach you... – dsollen Nov 19 '15 at 18:55
• You could steel star trek stealth systems. – PCSgtL Nov 19 '15 at 18:56
• Also, if they space industry of your universe is not as advanced as in the Honerverse than space infrastructure is significantly more important. They are the primary target. There are fewer of them, so they are also easier to concentrate your defenses, or to set up mines and traps. – PCSgtL Nov 19 '15 at 18:58
• thinking about it more. My problem is that I set up systems to encourage close range fighting, because I want fighters to be used and be able to close on an enemy ships without it taking hours. At such close ranges space isn't so vast, it's hard to hide when so close. However, my system also has massive electric radiation during battles, due to large energy outputs being reflected by shields as bursts, which make communication difficult. I could make stealth tech work pretty well during a fight by camouflaging with the ER. All I need to add is large ER radiation when a jump happens – dsollen Nov 19 '15 at 19:21

From a Hard Physics perspective, what you ask is exceedingly difficult to do. I'm going to approach this from a hard physics perspective which means telling you some of what you want isn't possible or realistic. However, since you're writing a fictional book, you may include rational or McGuffinite to make what you want acceptable in your universe (e.g. a no AI social taboo?).

## References

There's a very long and currently still on-going discussion over at Rocket Punk Manifesto about what "realistic" space combat might look like (please read the WHOLE thread on this - this is just the first entry). I happen to agree with most of the conclusions but strongly disagree with one of them (the NO stealth rule).

I also highly recommend studying at great length the website Atomic Rockets section on Tactics

## Throw out some standard tropes

Some of the standard SF tropes that are highly unlikely in a Universe with "realish" physics. In no particular order:

** I disagree with the "No Stealth" rule. The general reason why you won't find stealth in space is because if the enemy knows where to look, a Hubble Space Telescope (a HST) sized sensor could spot any ship at quite a long distance. Furthermore, a HST sensor could spot a ship accelerating at the levels indicated in SF books almost anywhere in the Solar System.

However, the Earth regularly has large (km and larger) sized rocks zip by and we don't notice them until just before or after they swing by.

Why is this?

Two reasons:

1. they come at us from the direction of the Sun and that makes them harder to detect.
2. we don't know where to look for them (we could still find them under condition #1 if we knew where to look).

So I consider stealth extremely difficult but not impossible to achieve.

EDIT: 11/22/2015 I'm going to rephrase this because really "stealth" is not possible. If the enemy knows where to look, they will see you.

What might be possible is to make yourself insignificant enough that they will overlook you for a while. Bear in mind that any maneuvering, firing energy weapons, approaching too fast, or getting close will result in your discovery. The first two resulting in instant discovery while the second two will just increase the chances of discovery.

Also eventually, you will be noticed. So this could be a source of interesting drama/tension in a space combat setting. A kind of Das Boat situation for the people on the "stealthy" ship.

## Tactics

It's impossible to provide you with a set of "tactics" that would apply to your situation. There's way too much ground to cover. Instead, I'm going to tell you how various aspects of your Universe may affect tactics.

### Details which affect tactics

• Spacecraft Thrust/mass ratio (this will give you their acceleration capabilities - maneuverability)
• Engine $I_{sp}$ (this gives you the ship's endurance capabilities - how long your engines can run and total $\Delta V$ available)
• Fuel tankage and remaining fuel (affects $\Delta V$)
• Directed energy weapon (DEW) limits (size, power, efficiency)
• Availability of high power engines for missile buses (which would replace fighters)

The details of the weaponry (e.g. engine performance vs. DEW performance) will strongly affect the balance of power between ships with beam weapons versus missile weapons.

Ships with beams might tend towards large sizes for massive "spinal mount" free-electron lasers (FEL). The FEL provides good efficiency (especially compared to most other laser technologies) which means more power and less waste heat to deal with. The large beam resonance cavity and ability to tune the laser to high frequency photons means the weapon might have the ability to destroy other ships out to a light minute (11,160,000 miles / 13,392,000 km) or more. Targeting and hitting at the range is left as an exercise for the reader, :)

Missiles can theoretically destroy targets anywhere in the Solar System. Whether they are viable as a weapon during a fleet engagement will depend upon their the ratio of missile acceleration vs. ship acceleration ($\frac{a_{missile}}{a_{ship}}$). If the ratio is > 1 then missiles may make good weapons for an engagement. If < 1 then missiles wouldn't make good weapons for an immediate confrontation but might still make good weapons.

The other consideration is the ratio of the missile's $\Delta V$ compared to the ship's $\Delta V$ ($\frac{\Delta V_{missile}}{\Delta V_{ship}}$).

If:
$\frac{a_{missile}}{a_{ship}} < 1 \text{ and } \frac{\Delta V_{missile}}{\Delta V_{ship}} < 1$
Then missile is more like a mine, you have to hope your enemy overruns the weapon.

$\Delta V_{missile} >> \Delta V_{ship} + V_{differential}$
Then missile will always hit the enemy unless it is shot down.

$\frac{a_{missile}}{a_{ship}} >> 1 \text{ and } \Delta V_{missile} > \Delta V_{ship} + V_{differential}$
Then missile will usually quickly hit the enemy unless it is shot down.

For other combinations, your tactics may determine whether the missiles can hit the ship.

For example, your missiles will can only hit an enemy running directly away from you if either the missile $\Delta V$ or acceleration exceeds the enemy ship's. Even if they do, the missile still might not hit that enemy depending upon the velocity and acceleration vector physics of the encounter.

### Tactical Goals

The goal of your tactics are to either engage your enemy or evade your enemy. Whether you can do either of these depend strongly upon your engine performance. In general, engines with high $I_{sp}$ tend to have very low, even minuscule thrust and vice versa.

If your ship possess superior $\Delta V$ (a combination of fuel tankage and $I_{sp}$ to your enemy's ship, you will always be able to force an engagement. However, if your enemy possesses superior acceleration, he may be able to determine when/where the engagement occurs.

Also it is a near certainty that the two ships / forces are not on parallel or reciprocal courses. Which means figuring out engagement attitudes, timing, where to place your weapons fire, etc. are all determined by tactics too. If you need to board the enemy vessel, then you not only have to match your 4 temporal-spatial coordinates, you also need to match your velocity vectors - not an easy task. What sort of accelerations can your crew tolerate? and for how long? Is it best to give your a crew a break before you enter the effective range of the enemy's beam weapons? If you can figure out where your opponent will be, your missile buses can get their first and force the enemy to fly through them.

If your tactics work or fail (depending upon the goal), then the combat resolves as who is able to stay away from the other's weapons. You want to go to where your opponents missile buses are not and force your opponent to move to where you missile buses are. You also need to arrange your ship so that it can fire any beams it has upon either inbound missiles or the enemy ship.

As I mentioned above, please read the linked resources, this topic requires quite a bit of thought and discussion

### Instead of fighters...

Fighters were developed as a means of attacking the enemy at long range - longer than any artillery. Instead of manned missiles, we have humans pilot a vehicle which then launches the ordnance. Even now in our current era, we are slowly replacing piloted vehicles with AI or remotely piloted ones. In a dangerous environment, like a space battle, it will be far more advantageous to use an AI which can survive 100G accelerations and not require life-support than to place a human in there.

For these reasons (and many more), it makes more sense to make a vehicle designed to carry the missiles to their individual launch points. You can call this vehicle a "fighter", missile bus, drone, or something else. Also the missile bus will be traveling away from the launch vessel at high velocity. This makes it difficult to recover. Instead of expending enormous resources to do so, simply make the bus part of the expendable weapons package.

So you might not have "fighters" so much as a disposable missile bus (with many missiles/penetrators per bus) doing the same job (transporting the penetrators into range of the enemy). Per the Honor Harrington Universe, the bus may have secondary roles (tactical computer for the penetrators, sensor platform, comm relay back to the launching ship, etc.)

Another possibility is something the game Traveller describes as "Battle Riders".

In your universe the Battle Rider Tender (BRT) possesses a high $I_{sp}$ engine. This gives the Tender the ability to do a lot of movement and get to higher total velocities than any of its riders. I will not be equipped with combat systems, because it is not intended to ever go into battle. The BRT fulfills the role of a carrier in a Universe with fighters.

The Battle Rider possesses high thrust (low $I_{sp}$) engines for maneuverability. This increases their survivability in combat but severely limits their $\Delta V$, which would be tiny compared to that of their tender.

## Another perspective on Terrain

Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space.

Unless the engagement is intended to attack or defend a "stationary" (in this context, stationary means non-accelerating) object (planet, spacestation, moon, etc.) you will not need to contend with terrain as we typically understand in the context of conventional terrestrial warfare.

Instead, you do need to contend with the "terrain" of relative position, velocity, & acceleration. The orientation of the the velocity & acceleration vectors will determine who is "downhill" from whom. For instance, in a tail chase scenario (one ship running away from another), the lead ship has several advantages. Some of these are:

• Lead ship can hit the trailing ship with missiles that possess both lower $I_{sp}$ and lower $\Delta V$ than the following ship (essentially they're like mines).
• The trailing ship's velocity and acceleration vectors are more tightly constrained making them an easier target to hit with all weapons.
• The flight distance of missiles fired from lead ship at trailing ship is MUCH shorter than the separation distance between the ships, so missile $\Delta V$ (analogous to range) appears to be greatly extended.
• The flight distance of missiles fired from the trailing ship at the lead ship is MUCH greater than the separation distance between the ships, so the trailing ship must survive incoming fire for a significant period of time in which it cannot fire back with a reasonable chance of a hit.

There is at least one major advantage for the trailing ship:

• Except for the special case in which the velocity vectors are aligned, the trailing ship will always have to travel less distance to get to a given point than the lead ship does. If the lead ship maneuvers in any way (e.g. evasively), then it allows the trailing ship to gain on them (in distance and velocity).

Each different distance, velocity, & acceleration profile for the two ships gives different advantages and disadvantages. If you look at these engagement profiles as "terrain" than it provides a unique insight into the types of trades a combat officer might have to consider when figuring out how to approach a hostile ship. You can see where it might take months for ships with realistic engine and fuel tank performance to get set up in an optimal engagement profile.

The pre-battle battle would in the most abstract way resemble a chess game. With move and counter move. Accepting or declining various options (e.g. in Chess, a black player may offer to exchange a pawn for the advantage of gaining the initiative). Move and counter move going into space combat will be filled with such tactics and trying to figure out the opposing ship captain's true objectives, weaknesses, and strengths.

• Great detail thank you. However, while I am trying to stay as hard as I can, ultimately I was trying to make a certain world exist and so I'm trying to make up technologies which justify it; even acknowledging that ultimately I'm losing some 'hardness' in dong so. So yeah, the space fighters stay, even knowing they aren't 100% realistic, because that's the entire genre/trope I started with and want to write (originally it was inspired by gundum, but I can't justify humanoid robots, I have limits on how far I'm willing to bend science to my needs lol). The rest is great details though. – dsollen Nov 19 '15 at 20:34
• I added a blurb at the top of my answer to that effect. Although it isn't realistic in this universe, it may be in yours. If you choose to keep them in though, I hope some of what I said can be helpful in developing the drama, tactics, or realism of the story. – Jim2B Nov 19 '15 at 20:36
• The reason we don't see rocks in space is because there is only one HST, and very few dedicated systems actually looking for incoming space debris. In a setting where there is commercial and military space flight, there will be lots of sensors, and you can "see" the Space Shuttle sized thrusters as far away as the asteroid belt, and the SSME as far away as the outer solar system. You just need someone to actually be looking. – Thucydides Nov 20 '15 at 1:17
• But this is exactly why you may be able to "sneak up" on another ship. They will have a limited sensor suite too. But if the sneaky ship uses typical SF powered engines, they will be seen. If the sneaky ship looks like a dead rock, they have a chance (which is not a guarantee) of getting much closer before being noticed. – Jim2B Apr 14 '17 at 20:02

The Rocketpunk Manifesto and Atomic Rockets sites are always great references for anything "hard" in space opera, and you have set up a very difficult situation to deal with in a "hard" setting. If we are to believe Rocketpunk Manifesto, space fleets will be constellations of fire support platforms moving in a majestic orbit towards the target, and most of the manoeuvre will have been done and calculated months or years in advance.

There are a limited number of places tactics can come into play: either at the beginning; you launch the constellation in such a way that the final target is ambiguous until they make their final burn, hoping the enemy will guess wrong and launch their constellation towards a different point; or at the end; The constellation does its burn when you don't expect it, so they are not entering the orbit you though they would be going to.

The second option is far more likely, especially if the constellation is entering something like the Jovian system.

Once in system, the other application of tactics is manoeuvring your constellation so that they have maximum sensor coverage and minimize any "blind spots" such as behind planets and moons in the system. Around Earth this is blindingly simple; establish a "sphere" of sensor and piquet drones across cis-linar space (most likely in the region of the "Hill Sphere"), while keeping the constellation in a fairly compact formation to maximize firepower.

In the Jovian system, there are far more hiding spots (including burrowing below the surface of the various moons and using them like airstrips or aircraft carriers), as well as various hazards like the radiation belts and ring system, so there will inevitably be blind spots in the sensor coverage. The enemy will have to determine where the sensors are, and exploit the blind spots to move. The constellation will be in a compact formation no more than a light second across to maximize their situational awareness for a fine grained 3D view of the system (outlying sensors will be beyond the light second ring, so their input will have a distinct time lag). This means that even if/when you get the jump on them, they will be in a powerful fighting formation.

The last tactic that can be used is deception. IF all the spacecraft are roughly the same size and shape, you might discover too late that you are doing an attack run on a Laser Star armed with a terrawatt Xaser (that would tend to ruin your day out to the distance of one light minute), while a similar spacecraft might be a missile platform (Kinetic Star) or even a carrier for your fighters. If you are very lucky, it is only a fleet tender or tanker...

It's true that tactics often revolves around taking advantage of terrain. And that there isn't much terrain in space.

But:

There is SOME terrain: stars, planets, moons, asteroids, etc. Yes, in real life space is much more empty than you see in movies -- the asteroid belt is not really the densely packed field of rocks that ships have to dodge and maneuver around like in the movies. I'd guess that it is unlikely that more than one planet and maybe a moon or two would be relevant in any given battle. Star Wars actually had an intelligent -- I thought surprisingly intelligent for a campy move -- use of the orbit of a moon playing a role in the tactics of a battle.

But more important, tactics on Earth is not JUST about terrain. Throughout history armies have often sought out wide open spaces to fight so terrain wouldn't get in the way. And they don't then just "go at it", but attempt to outflank each other, probe weak spots, etc.

Air and naval combat is fought in environment just as open as space, and they still use tactics and maneuver. They don't just face each other and start shooting.

In any form of terrestrial combat, common tactics include:

Mass: Maneuver the enemy into a position where many of their units cannot fire, while all or most of yours can. For example, get them where many of their units are out of range, on the fringes of the battle, or where their own units block fire.

Flanking: Position yourself on two or more sides of the enemy, so they have to deal with attacks on two sides while you only have to deal with one.

Fresh reserve: Withhold units from combat until a critical time, so you have units that are alert and unhurt while the enemy is tired and damaged.

Surprise: Do something that the enemy does not expect and is not prepared for. This doesn't have to mean gaping, open-mouthed astonishment. It could be as simple as attacking place A when they expected your attack would come at place B, perhaps because it was the "obvious" place to attack, perhaps because you planted misinformation, etc.

Etc.

Specific characteristics of weapons can lead to specific tactics.

For example, during the age of sail the British figured out that ships of necessity are longer than they are wide, and so can fit many more guns along the sides than at the bow and stern, and so if you "cross the T", i.e. position your ship so that your side is facing the enemy while his bow or stern is facing you, you can fire with many guns while he can only fire with a couple.

Since the beginnings of air combat pilots have figured out that getting "on the tail" is the key to winning in aerial combat. Position yourself directly behind the enemy. The pilot's easiest view is forward and weapons fire forward, so you can shoot at him while he has a hard time even seeing you.

You'd have to think through how your proposed space warships work to come up with analogous tactics. Of course you have the advantage in SF that you can think of a tactic first and then invent technologies to make that tactic work.

I know you specified somewhat hard sci-fi. But you already have one big handwavium technology - shields. What if we use that to add a somewhat limited stealth capability?

Think about what shields do - they deflect mass... and energy. What are sensors? Various forms of reflected energy.

Make it so shields can be calibrated to a stealth mode. It's not 100% perfect - possibly they create a tiny "cone" in which the ship's signature is still broadcast, and maybe even enhanced. But for anyone outside of that small cone, the ship is effectively stealthed.

You now have surprise, which gives you tactics. But it's not perfect:

• Since fighters are too small to be shielded, they need to be brought into position by stealthed carriers until the actual fight starts.
• Since shield tuning and resonance is so important, a stealthed ship is - by definition - an unshielded ship. So stealth = vulnerability.
• Presumably higher powered sensors might break the resonance and reveal the stealthed ships. These might be in place around fixed installations but are too expensive energywise to be used constantly on capital ships. It also means stealth probably isn't possible if you get too closed to a star... although maybe it would be possible to blend in?
• You might not be able to stealth all frequency bands simultaneously, which would make the hunter/hunted cat and mouse game more interesting, as sensor operators try to guess and tune around their enemies, while stealthed shield technicians do the same and try to keep ahead of them.

Decoys.

It would presumably be much cheaper to produce inanimate hulks of similar size & composition to your fighters & bombers than to produce an actual vehicle. Especially with the smaller vehicles coasting in at minimum power before the shooting starts, it will present the enemy with a challenge to pick out the relative handful of actual vehicles among the crowd, forcing them to spread their defensive preparations across a wider range of possible attacks. The larger the number of objects, the more effective this will be (10 decoys for 10 ships probably won't have a meaningful effect; 10,000 decoys for 100 ships should).

Of course once a ship actually maneuvers or fires it'll be a known threat; at best you could attack in waves to force the enemy's attention to remain at least partially on the as-yet inert objects to guard against delayed strikes.

• +1 I think this is one good counterpoint to the "no stealth in space" arguments. It might be hard to be completely invisible, but it would probably still be possible to deploy many decoys of different types, and to make your actual combat units hard to identify and distinguish from the decoys. – Dronz Nov 21 '15 at 16:22

This started out as a comment, but I decided it's actually a fair answer, so here goes.

You don't really say much about how your sub-lightspeed drive system works, so I'm going out on a bit of a limb and assuming that it relies largely or entirely on Newtonian or relativity physics. In other words, what we've got in our world.

In such a situation, in spaceflight, you don't use the engines very much. In fact, you want to turn the engines off and coast as much as you possibly can, in order to conserve fuel. Look at this graph of the rocket equation:

$\Delta v = v_e \ln \frac{m_0}{m_1}$

That graph shows the spacecraft's mass ratio (total mass including fuel, to total mass excluding fuel, on the vertical axis) as a function of its ability to change velocity (on the horizontal axis; $\Delta v$ is the total velocity change budget, and for all practical purposes, $v_e$ is a constant for a given engine). It starts off fairly reasonable, and grows exponentially.

This leads to an obvious conclusion: If you can afford to coast, you can conserve your fuel for maneuvering when needed.

So a potentially advantageous tactic would be to coast as much as possible, making maneuvers that require as little fuel as possible while achieving the intended goal. Because any given maneuver implies a specific $\Delta v$ (change of velocity, along some vector), and the mass ratio grows more slowly if $\frac{\Delta v}{v_e}$ is smaller, this favors the engine technology with a larger $v_e$ or effective exhaust velocity. This puts some fairly specific constraints on spacecraft engine design, and the civilization that can make engines capable of meeting the required $\Delta v$ at the higher $v_e$ will have a maneuvering advantage, regardless of whether this is for combat or peaceful purposes. The spacecraft that is slower to maneuver will be a sitting duck as it coasts along in its orbit, blissfully unaware of the weapons being fired toward it. Some of the implications of this are discussed in this answer to How much bigger could Earth be, before rockets would't work? on our sister site Space Exploration.

In science-fiction movies, we're pretty used to seeing spacecraft with engines on all the time buzzing around each other, like aircraft or seacraft, but such a tactic would, in real life, mean you run out of fuel very quickly. Due to the exponential nature of the rocket equation, you just can't afford to carry all the fuel that would be required. Figure out ways to make do with less fuel, and you'll have an advantage, whether you use that advantage to allow for more maneuvers or for more lightweight spacecraft. Just because something is "weightless" doesn't mean inertia is unimportant.

• In SF movies it's also common to see spacecraft bank into turns like an airplane, using air resistance to create a force shifting the direction of travel. Well of course in space it's not air resistance, so it must be ... ummm ... vacuum resistance? The mechanics of combat in a vacuum would be very different from the mechanics of air combat, a fact that seems to have escaped almost all makers of SF movies. – Jay Nov 20 '15 at 4:10
• This is very true. Efficiency and fuel conservation and feints may be more decisive in many situations, than speed. And again, decoys - if you can get the enemy to waste a lot of their fuel maneuvering against your decoys, then your actual forces may be able to get a decisive maneuver advantage over them. – Dronz Nov 21 '15 at 16:25

In one sci-fi novel I read (the name escapes me), ships would launch swarms of missiles long in advance. Those missiles, being relatively small, and difficult to detect, would fly to certain locations in the solar system, power down, and lay in ambush.

Your fighter force might do the same. You detect the enemy: there's only so many trajectories to get from point A, to point B. Your capital ships place themselves such that they attract the enemy in a certain direction.

The small fighters, powered down to minimum life-support, drift into position slightly further away. When the enemy fleet closes in to engage the capital ships, the fighters power up and attack from a completely unexpected direction.

Of course this requires the ability to plan your engagement well in advance, and maybe even to deploy some kind of refuel ship with the fighters.

Keep in mind that the vastness of space is in fact the best cloak. We can barely keep track of a fraction of what's going on in the night sky. If these ships restrict their communications and power down outside lights, they might become just one more hunk of junk drifting through space. No one's going to "look out the window" and see them. No one would know where to look. In the mean time, they can keep track of their enemies using passive scanning equipment.

• sound an awful lot like the Honor Harrington series referenced by PCSgtL actually :). I don't recall that particular strategy exactly in the books I read (I didn't read all of them, I couldn't keep up with so many characters being bad with names), however, I almost gaurentee it came up at some point in the series, giving all the stuff they did do with missiles :) – dsollen Nov 19 '15 at 19:08
• I never read that series, but I'm sure it's a common theme, as it's a very logical way to conduct space warfare (depending on the technology). – AndreiROM Nov 19 '15 at 19:22
• Unfortunately a "powered down" fighter is still very visibly warm compared to natural space objects, so this doesn't really help. You can maybe do it with missiles, assuming they can survive ok at what we'd considered very low temperatures, but a manned fighter? Iffy. – Dan Smolinske Nov 19 '15 at 19:44
• @DanSmolinske mass effect tried to address this, by setting up heat sinks that could store the heat produced for some time. eventually the heat would have to be output and light you up, but you get a brief period of 'stealth' of course smaller fighters/bombers couldn't fit a very big heat sink, so I doubt it would work for them. – dsollen Nov 19 '15 at 19:51
• @dsollen - the heat aspect is a very good point - if you have sensors sensitive enough to detect some heat across the solar system, or even a few thousand kilometers away/anywhere in a bubble around you. The problem is not heat, IMO, it's electronic signals. – AndreiROM Nov 19 '15 at 20:15

How about your spacecraft make their own "terrain" in the form of (un)controlled debris fields?

A debris field would neutralize any weapon fired from a distance. That mean engagements would need to be close ranged and require quick decision-making when weapons are fired (a possible reason not to use AI).

The capital ships would launch several large fields, possibly with limited maneuverability. The fighters could have smaller fields, possibly even built into their design (I'm picturing something like the skyjacks in Jupiter Ascending). System defenses would have large debris fields with heavily defended navigation routes (and lots of dangerous, uncharted routes for enterprising fighter pilots to exploit).

Tactics would mostly resolve around positioning. Block the enemy's fire lanes while opening your own. Feints, hit-and-run attacks, hiding-in-the-debris, stuff like that.

Spacecrafts and fuel are expensive. This leads to everyone being very risk adverse. You don't really want to go into battle unless you have your opponent at a great disadvantage.

As you can't ambush a fleet from behind a planet, you'll have to find another way to get a large advantage. You'll need to attack the enemy when they are very low on fuel.

This means that you must move your own fleet around, threatening attack after attack until they are far from their jump points and low on fuel. This would be easy if you have many battle groups of the same size and firepower as your opponents single battle group. But if your fleet is of the same size you would have to split up in smaller groups, threatening attack, but never get into a position where the opponent can counterattack because you get too close with too small a force.

You may even be forced to sacrifice one or more capitol ships to destroy the opponents tankers to get a sufficient fuel advantage.

• I like this comment, though I would do exactly the opposite of it lol. In my world the main protagonists have a single carrier, or later a very tiny fleet, but within it the carry a small number of absurdly expensive, and potentially very lethal, specialty weapons. They should be more maneuverable because they aren't in a fleet, they don't have to wait for the entire fleet to maneuver together to make turns; but they still carry enough threat in their cargobays to make enemy fleet unwilling to split up. This gives some room to harass and maneuver.. – dsollen Nov 20 '15 at 16:18

You mention quite a lot in your question, so I'm only going to focus on one topic:

I have a setting with space fleets fighting, they include both capital ships and human flown 'space fighters', which I already put some work into justifying: How to keep humans pilots instead of AI in sci-fi future?

Use EMP weapons. Humans won't be killed by them, but as for AI...you'll need a pretty big Faraday box to put an artificial intelligence in.
Or you could rely on the fact that AI are almost always going to have exploitable loopholes in their logic.

• An interplanetary spacecraft with all electronics fried is going to be an uncontrollable, deadly hunk of metal moving at a minimum of 15 km/s or so relative to essentially anything relevant. I'd wear a helmet. – a CVn Nov 19 '15 at 23:22
• True. But you could put the electronics in a Faraday box. You can't do this with an AI system because it would need sensors to measure the outside world; if the sensors were safe from EM radiation, they'd be useless. – Wick Nov 20 '15 at 1:25
• I linked a question that already focused on this, both things you mentioned were there; it was somewhat popular so it got quite a few great answers. Just for the record something like this may be better as a comment, as it is not an answer to the specific question but instead a comment on a side issue within the comment. I still appreciate all ideas, just want to explain the SOP for newer folks. Speaking of which welcome to worldbuilding :) – dsollen Nov 20 '15 at 16:14

Space tactics, maneuvers, etc naturally vary for a variety of reasons.

Different ship classes

Making everything a big cruiser has it's downsides. Smaller ships are able to outmaneuver bigger guns, fly largely undetected. Logistics transports carry large amounts of supplies and don't incur the same costs as building big, and are often necessary in large scale fights.

Then you have the defensive classes - anti-space mines, anti-missile defence, anti-fighter classes.

Space is 3D

Hiding behind planets, moons, etc, is an old-school rookie mistake. That's the first place any seasoned ship commandeer would expect you to be. Hiding in nebulae where sensor locks are impossible, or even playing chicken with the event horizon of a black hole (which inexperienced commanders in large ships with a lot of mass often fall for - literally) is where make-or-break happens.

Ships can attack from above, below, on the Z axis. Some rogue elements have been known to sit in cloak weeks at a time in a single spot where a neutron star covers their low-power sensor profile, only to attack when a group of carriers have their shields down and are conducting repairs in an area that has been safe for some time.

It's all about location, location, location

Big fleets are nice, but what if you were at Rembabuun 3 on defence, when the enemy instead raided space station Kotoon and destroyed a couple of your Drydocks whilst they were at it in the Contar sector, at least 30 minutes away?

Stretching your fleet to 'defend everything' is a huge no-no, as it allows isolated battles to occur and holes in a defensive net to form. Half of the battle is disinformation, the other half, secrecy and surprise.

Space is big

And so is your border. Border patrols aren't a thing. Instead, most commanders defend 'key areas' either with static defences or big fleets, with roving 'hunter-killer' groups whose goal is to hunt and track down other fleets in space for engagement.

No-one obeys the rules

Geneva convention didn't apply when the Intergalatic Fleet or Imperialic Fleet built their superdoom weapon and started firing into fleet engagements at random. The second moon of Yonkoon blew up, taking with it a main space trading station. 'It was an accident', according to reports. The Intergalatic Convention on Space Rights doesn't have it's own spacefleet, so it's highly dependent on the already-at-war parties to enforce it's toothless laws.

Political will changes tactics

The Peacekeeper Corp of the Seventh fleet are adverse to killing pretty much anything. They're comprised of volunteer medics who respond to disasters and warzones. Their idea of 'tactics' largely involves running away, or sometimes wading in regardless with a big sign indicating they're medical only. To some fleets, that's a giant target.

The Patriotic Corp, is an independent ragtag fleet of ships (pirates?) who, on the other hand, aren't so adverse to violence. They've been known to purposefully murder survivors to keep up their terrible reputation, pillage ships for supplies, and sometimes even rig civilian ships to fly into military ships on auto-pilot with enough explosives to make a Gangoolian wet it's brine container.

Go play EVE Online. Seriously. See how tactics work in that universe.

Most of them revolve around "on grid" combat, and rock, paper, scissors.

You can use this as well.

• If a ship is too far away, you can tell "something is there" but not "what".
• As it gets closer, you can tell the "what" but not exactly.
• As it gets "on grid" (actionable in the game), you can tell more precisely the "what".
• Bigger ships (and such) have the ability to "hide" forces. Either because you can't tell what is docked in a "Capital Ship", or because the large ships can "jump in" smaller ships.

Then

• Small ships have smaller guns.
• Big ships have big guns but can't really hit smaller ships.
• Lots of small ships > 1 big ship.
• 1 Big ship vs. 1 Small ship = No win. The small ship can't damage the big ship, the Big ship can't chase down the small ship.
• Special ships have a well defined role. A scanning ship can do much damage. A "tank" can dish out massive damage. A "gun boat" can really pump out damage but can't take as much. A fast ship can't do much damage, but is too fast to take a lot of damage.
• Big ships are needed to fight big ships
• Small ships are needed to fight small ships.

Quite a few tactics have evolved around these rules. The biggest is that while space is big, and vast, your fighting has to take place in a small area. In the game it's usually around a fixed point, but it can take place at a random location. It's just that all things in combat have to be "on grid".

Mostly though, you end up with the same "rules" as present day warfare. Range, accuracy, and the ability to specialize make the difference. A rock paper scissors approach. Which, exists today in naval combat. That's why, no matter how impressive a Battle ship is, it is not sent out without an escort of other ships.

Imagine the fight is between nano-robot probes, that have an extremely slow computational speed because they have very little computational power. These probes could maybe have a processing speed of a millionth of the human, and so "in their opinion" the fight would be very interesting and strategic.

You can have huge numbers of these for each army, that must juggle their power between computation, locomotion, attack, defense.

You can elaborate on the "swarm" mentality, maybe a single probe is low tech/stupid but ten thousand can create a jamming / intercepting network that can be more dangerous than the sum of its parts.

This can create an interesting environment, where the probes do not communicate with each other too often because they need the energy to move out of the enemy's trajectory.

This could all just be a hobby of "superior beings" so advanced we cannot comprehend that can live for billions of years or more (nobody really knows).

As an addition to the answers above, your shields could heavily influence the range at which fights take place.

Imagine an enemy pops up a few lightminutes away. They detect eachother and open fire. You dont just create a shield bubble but a shield wedge: the ballistics fired at it will basically hit a giant sloped armor and are likely to bounce off if the calibration was good. lasers already fan out too much for effective long-range combat so it would be mainly ballistics and missiles. Missiles and other computer and AI can suffer interference from the shield, hence that not just the fighters but also the capitol ship are manned rather than AI governed (I'm still at a loss why people would argue that fighters would fly with AI while capitol ships would still be manned? Why would you not remove the human element and AI your entire fleet?).

Anyway, the shield might not be alterable on a dime, so being close and able to have a high angular velocity allows you to avoid the wedge shape of the shield and do full damage against the shield while fighters can be close enough to require being manned and not be auto-targeted and killed by automated systems.

One idea that comes to mind is using the shields to stealth the ships, simply use them to block all the heat emissions of the ship and suddenly the battle turns into a game of hide and seek with nuclear warheads. Your protagonists would need to carefully plot their movements to avoid overloading the shields. Every battle would become a battle between minds, as the captains of each ship try to predict what the other is going to do next.

Create your own space terrain

Space is big and empty ... but what if you could change that?

You can use things like the space equivalent of shotgun shells that scatter high velocity debris over a wide area, or some sort of constant jamming technology to deny your opponent control of sections of the battlespace and try to force them into an unfavorable position.