Army composition in a "Dies the Fire" scenario

Question

For those not familiar with these books: Dies the Fire* and the subsequent novels by S.M. Stirling are a fantasy companion to his Island in the sea of time series where Nantucket is sent back in time to roughly 3500 BCE.

In summary: all electricity, gunpowder and advanced power generation ceases to function, because the "Alien Space Bats" wish it so. Nothing more advanced than muscle power and torsion mechanisms (i.e. catapults) is available anymore. The survivors, for some reason, choose to recreate various epochs of human history (Gaelic Clansmen, Normand knights, Vikings, Plains Indian horse nomads etc.).

I've just started my role-playing group in this setting and the characters are busy trying to survive the "Change", complete with "Stop Sign" shields and steak knife daggers, but I plan on jumping them forward in time soon so I'm looking for ideas of how people, unencumbered by the needs of selling paperbacks, would go about organising their armed forces.

I'm leaning towards mixed units of pikes and crossbows with auxiliary light cavalry simply because it's probably the most effective absent cannons and other artillery, but I might be missing something. What would be the most effective military unit under the above constraints?

Clarification:
What I'm asking is: given that the survivors will have at least some knowledge of history and in pre-firearm militaries in general pike and crossbows (along with auxiliary light cavalry) are the most effective armed forces organisation, as opposed to say heavy feudal-style cavalry or Roman Legionnaires for example, what would be the most effective military organisation someone with modern day knowledge could come up with?

Once the society has recovered from the Change and has started to rebuild itself into an expansionist state it will need a military and it will obviously try to go with the most effective one.

Given that what disappears in the Change is the technology of modern warfare, not the knowledge and human experience we are going to see most societies recreating pike and crossbow as it is. This is because this military organisation is, as far as I'm aware, one of the most effective pre-gunpowder troop formations. Or are there other ones that people with modern military knowledge might come up with?

Answer 1

Let’s begin with discussing why “the Change” doesn’t set us back nearly so far back technologically as one might think. The Change removes our ability to power our tools by chemical, electrical, and pressure methods, but the world had developed a great deal of industry before any of those power generation methods existed. Factories ran off water wheels or simple man and animal power before steam engines were used. We figured out the fundamentals of precise machining and the mass production of interchangeable parts on man-powered lathes and mills. Electrification only began in earnest around 1900, so any technology from the 19th century not otherwise directly precluded by the Change is likely still workable. This means that given enough time and stability a post-Change society will rapidly advance to a fairly advanced technological level with a third industrial revolution. The main disturbance of the Change is not so much the actual limitations it imposes, but rather the disruption of civilization and the chaos and death that will ensue. With all that said onto military matters.

Chemicals

The most powerful weapon on the post-Change field is going to be chemical weaponry. With 21st century know-how, many industrial chemical processes are going to be achievable even without electricity. They may even be easier because the volatile chemicals are incapable of exploding or building up significant pressure making the whole process relatively safe. Many methods can be utilized to deliver these toxic substances from trebuchets to crossbows to man-powered hoses. What these weapons will do to warfare is hard to predict as they never existed in the absence of superior gunpowder weapons, but they will undoubtedly be effective. In a world where it becomes much harder to deliver enough force to kill or incapacitate a man, the ability to kill or incapacitate without force becomes indispensable.

Fire

A related weapon is fire. Flamethrowers today use pressurized tanks to propel burning napalm hundreds of feet. Napalm or a similarly flammable liquid is relatively easy to create and will be a useful ammunition type for trebuchets and crossbows. We can also construct flamethrowers though. Without the use of pressure, we will need to use a different method to fling our flaming liquid. My thinking is that a centrifugal pump will serve well relying only on the motion of a man-powered crank to propel the napalm. A team would be needed to operate this weapon and with the various tanks and gears, it may be quite unwieldy but practically unapproachable by infantry. If you want to get crazy one might even imagine an armored vehicle of sorts where bicycle pedals are used to power movement and once in position can be switched to power pumps and operate a powerful turreted flamethrower.

Centrifugal guns

Lastly, a more eccentric weapon is the centrifugal gun. As early as 1828 a man named Robert Mccarty had designed a centrifugal gun. 6 men used cranks to spin up a disk. An operator then feeds 1-inch diameter balls to the disk which are rapidly accelerated and shot out of the device. These rounds could apparently reach ranges of nearly a mile but were quite inaccurate suggesting the effective range would be far less. The balls leave the weapon as fast as they can be fed in giving the machine a monstrous rate of fire of 480 rounds per minute. The US military seriously considered purchasing these weapons. While a far cry from a rifled automatic weapon these machines would prove extremely effective against groups of infantry.

Conclusion

I expect that together these types of weapons and more than we aren’t considering will preclude the use of close-packed infantry formations as they are entirely too vulnerable to such attacks. Cavalry charges as well are unlikely to be effective against such weaponry. Rather we are more likely to see guerilla type tactics involving cover and primarily ranged weaponry predominate. The most prevalent weapon will likely be the crossbow while the most prevalent method of transportation is likely to be the bicycle rather than the horse for several reasons. Bicycles will be much easier to find than edible horses in a post-apocalyptic society. Bicycles don’t require food or much maintenance and their parts are easy to find or produce if need be. The landscape is already heavily paved with roads that will make bicycle travel rapid and comfortable. With charges being suicidal horses provide little combat advantage over bicycles. Bicycles were even widely used by militaries in the earth 20th century before motorized vehicles became more commonplace. You could even modify bicycles into larger man-powered vehicles to carry heavier weapons if needed. One could imagine bicycle-mounted crossbow-wielding infantry acting as post-apocalyptic skirmishing dragoons. Whatever warfare post-Change looks like, it’s not going to resemble anything seen before.

Answer 2

I'm not too sure what your asking for beyond medieval army compositions but it looks fun so I'll give it a try.

From my perspective an army should consist of 1-2 lines of shield men followed by people with either pole arms or spears. The reason for this? The shields protect your people from the front and maybe some arrows, the pole arms are able to reach above and over the shield or through small gaps in the shield and stop people from getting close. The best example of how terrifying this can be would be in the Game of Thrones scene where John Snow and the Wildlings are being surrounded by this composition. It is extremely hard to break if you value your life, because the person who runs into a shield will more or less likely die.

Now what you want after this is your standard soldiers, probably using spears over swords. Why a spear over a sword? Its easy to train someone to use a spear, it requires less metal (only the tip) and it has a very long reach. In an army vs army situation, you point your stick at the enemy and the enemies are going to push themselves onto you. Thats not to say you won't have a sword, a sword would probably be your secondary weapon, so once the spear is used, you pull it out and start to fight it out.

After your shield wall, your main body of soldiers, you will mostly likely have your cavalry or archers. The cavalry would of course move out and try attack the flanks of your enemy. There won't be much shields on the sides because the enemy isn't expecting an attack from there. Of course, your cavalry would have a hard time taking on a row of spears so they will probably have a diminished role and be attempting to attack the back lines where your defenseless archers are situated.

Your archers are situated in the back, shooting away. You will of course have to be able to estimate their approximate range and make sure that your shield wall isn't going to be close to it. You don't want a stray arrow hitting your allies, so your archers are going to be aiming into the main body of the enemy, far behind the shield wall.

So thats roughly what I could consider as a basic formation. Of course this changes with terrain and resources available and then you also have to develop army formations based on who they are fighting. Going back to Game of Thrones, in the scene when Stannis defeats Mance, he easy wins because his armored knights are able to easily slaughter their way through barbarians who don't have the teamwork and training to deal with armed cavalry (e.g stick together in clumps and strike out at once and spears).

Then after you have terrain and resources taken into account you want to adjust your army formation more. Should they be in one big clump, maybe spread into smaller clumps. How would different units support each other and what are their different objectives.

Back to your suggestion of pikes and crossbows along with light cavalry, lets analyse how it plays out. My pikes are good vs the enemy cavalry but they can't move forward easily because they can either carry a shield and pike which means if they are hit by the horses when they are moving they aren't going to be as prepared or they can use just a pike which leaves them vulnerable to the enemy crossbows. If the pikes move out, your crossbows are suddenly vulnerable to the Calvary who are faster and once they are on top of your crossbow men it will be a slaughter. Your crossbow men can only sit there and wait, because if they move into the range of the enemy crossbowmen they will get shot first and if they move away from the pikemen they will be attacked by cavalry, the winner would end up being the defender.

If instead one army had a shield wall with polearms/spears/pikes mixed in, they can suddenly advance forward and start to put pressure on the defender. The shield stops the bolts with the polearms people hiding behind the tall shield. The cavalry are repelled when attacking the shield due to crossbow support and the long reaching pole arms. Once the shield wall is within pike range, the enemy cavalry and shield wall charge in from the front and sides. Behind this the enemy crossbow men advance and rain down bolts on you.

What I'm saying is that your army lacks shields, a key item to defend yourself from ranged and close quarter combat. It doesn't matter if its a Captain America style shield of if its taller then the person carrying it, it gives your men a safer way to move forward.

Also remember that pikes are good vs Knights on horses and in shiny armor. They would be less effective against infantry because they aren't designed to deal with infantry. A spear is shorted and more thurstable which makes infantry fighting easier but fighting people on horse back harder.

Answer 3

Has this got to be purely immediate military competition for a game or something?
One major thing I've learned from survivalist discussions here on Worldbuilding is that stealth is one of the most important factors in creating a defensive position. Don't attract attention with large flashy fortifications or other outward signs of wealth and prosperity. It'll only attract more raiders and eventually numbers will defeat any defenses and you lose lots of resources keeping a standing army at all times.

Crossbows are indeed very good for your purpose, especially since good metals are available to be scavenged. But don't forget armor either, modern alloys and kevlar will turn almost all edged and point weapons. And you can have a variety of types given modern alloys and keep them lightweight. Flechette launchers like shotguns and grenade type launchers for pressurized containers that can disperse irritants.

So no electric or hydrocarbon fuels or all that? Modern mechanical machinery still effective though. Wind power, solar, etc, can be used to drive machines, heat water and process food (an army travels on its stomach); and sunlight focused to do a lot of work fabricating materials. Modern lenses can do much to assist communications and surveillance.

Local ingenuity developing alternative ideas of "batteries" can be much to your use here. Using wind power to compress air and power air piston vehicles seems within the rules of your system, if not the spirit (and that's its biggest military advantage, surprise and confusion, and while adversaries are arguing if you're cheating, get on with business).

Next thing is to build up chemical infrastructure and produce at least basic medicines and fertilizers and even soap. Ammonia will allow refrigeration and along with other methods within your scope, food preservation and packaging.

But if this is a game that is merely a military brawl and you want the greatest brutality and devastation without gunpowder and chemical explosives, then things like burning tar, homemade napalm, pepper spray and other "natural" forms of chemical warfare can disorganize enemy troops and then pick them off with the crossbows.

The idea of returning to feudal times I think is wrong in that much that had a psychological impact before wouldn't be as effective. David and his sling took down Goliath because David didn't play into the game attacking on Goliath's terms (face to face with sword or club). I won't debate how all this "Change" is supposed to work (no electricity for machines but animals' nervous system still works) but it seems narrowly defined so the same ends can be achieved through different means such as compressed air vehicles and weapons and solar heat for metal furnaces, steam power, refrigeration and food processing.

With your armies, they will depend upon such traditional things as food surplus and training. Collecting engineers, science people, and skilled workers very important, especially those who can put to use as much modern tech as possible operating within the "Change" guidelines.
  I'd also make sure that weapons and facilities were of limited use to the enemy if captured; special quarrels for crossbows, booby traps, etc. Most important is not to lose a single battle and thus hand over tech or key personnel over to the enemy. Spies will be quite important but require a basis for loyalty such as a decent society (or good old fashioned extortion - holding their families hostage).
Super sucky that we're still vulnerable to such brutality as a primary option. I'd look forward to questions posted that ask about the best ways to establish diplomacy in a post-catastrophe world.