So the idea of space navies is extremely common in science fiction, with the navy as the branch that is more or less dominant. Generally speaking they have marines under them and there is rarely an army and even less frequently an air force structure that winds up mattering. This has led to a frequent debate about whether space militaries should follow air force or naval structures. In reality, given that air forces tend to be the ones who are building up the military presence in space, that seems to be dominating.

Though this led to a potentially more interesting question. How might a navy have historically been the ones to dominate aviation in the early days, such that a separate air force was never built?

Could this have then led to a situation in which a marine corps might actually more or less absorb the army rather than having the navy split off the air force into a separate branch?

There aren't any historical examples of anything like this happening that I know of, as armies tended to control aircraft over land until a separate air force was developed. While there were cases like Japan in which the navy also flew bombers, their army still had its own separate air force. In the US, the situation was far closer to the other way around, with the US Navy after WW2 struggling to find a purpose until they figured out a way to control a piece of the nuclear deterrent. Meanwhile the USMC was nearly on the chopping block given the successes of US Army amphibious operations with several politicians including President Truman arguing that the marines were mostly redundant.

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    $\begingroup$ ? The US Navy has its own air force, which has nothing to do with the US Air Force. AFAIK, this was always the case. The US Air Force is descended from the Army's air force, which somehow became a separate branch of service after WW2; but the Navy has always retained control over its airships, aeroplanes, helicopters and such. Those aircraft which fly off Navy ships are Navy aircraft. $\endgroup$
    – AlexP
    Commented Mar 21, 2021 at 21:00
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    $\begingroup$ My question was about how a navy would hypothetically control all aviation rather than part of it belonging to the army, so that they wind up with both the roles of the navy and the air force in the long run. $\endgroup$ Commented Mar 21, 2021 at 21:35
  • $\begingroup$ Early military aviation was shaped by the coincidence of two massive land wars. In the USA, for example, the navy dominated aviation development during the interwar period of the 1920s and 1930s, Remember that armies and navies have quite different goals, correspondingly different strategies to achieve their goals, and different structures to operate in support of their strategy. Fundamentally, how the top leadership of any military force is organized starts as a political question, so it can shake out many possible ways. Also note that USN (air) and USAF don't have much overlap. $\endgroup$
    – user535733
    Commented Mar 22, 2021 at 0:14
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    $\begingroup$ @bukwyrm probably the most important distinction is that Naval ships are designed to operate for weeks/months away from a base, have crews from a few dozen to a few thousand people, carry extensive supplies/spare parts with them, and do basic maintenance while underway. Aircraft are designed to operate for a few hours to a day or two max, only have a crew of a few people, carry minimal supplies as a result, and do almost all repairs/maintenance at the base by people who aren't part of the aircraft crew. $\endgroup$ Commented Mar 22, 2021 at 16:03
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    $\begingroup$ From there it follows that if you've got large ships flying around and conducting extended operations in deep space you've got a Space Navy. If you have fighters operating from fixed bases not mobile ships a Space Force with an Air Force culture is more reasonable. You're not required to do so - and certainly can build credible story reasons for not doing so (ex the Space Force flew fighters from Earth surface for many years before the technology/need for large deep space warships developed) - but messing with reader expectations always has a cost. $\endgroup$ Commented Mar 22, 2021 at 16:06

9 Answers 9


The Idea of the Air Ship:

Having a universal navy is more of an IDEA than a practicality. In a nation where having a significant navy is critical to defense of the nation, but armies are mistrusted as a threat to the various states (like in the early USA), there might only be a national navy by law, and states would regard a national army as a threat to their sovereignty.

But as a practicality, you need to be able to have soldiers that fight overseas. Sometimes, the national capital needs to be defended from foreign powers or even rebellious states. So the navy gradually institutes a marine corps to fill in as needed. This marine corps IS the national army in all but name, but that title, being subservient to the navy by law or constitution, is a critical one.

Now you have clever people building Dirigibles, and the military value of flying ships is obvious. These are big, expensive, and look like, well, SHIPS. An extended period of lighter-than-air craft would enhance the place of flying machines as air ships instead of air craft. So naturally, once heavier-than-air craft are built, they are called air ships (or if small, air boats), not air craft.

And finally, as land transport becomes mechanized, who understands the engines involved? Many of the first military armored vehicles were referred to as land battleships. The same concept can apply to your fictional state. While trains aren't military, land ship transports aren't a big stretch from tractors (even steam-powered ones), and you can have land cruisers, destroyers (tanks), and so on. You might have large parts of the 'navy' that never see the water, but by tradition are considered naval units. A number of 'land battleship' concepts have been floated around (pun intended) and would have stood a better chance of development by a nautically-focused military.

Eventually, the militias that were the backbone of the original army fade away as all forces become naval (synonymous with national) forces.

  • $\begingroup$ +1 for the answer, if I could give another +1 for the pun I would :) $\endgroup$ Commented Mar 23, 2021 at 16:25

If you need a boat to go any distance.

archipelago sea

Depicted: the Archipelago Sea in Finland. If your world were nothing but small islands, you would need boats for any interaction between large groups of people and that includes war. We have armies in our world of big contiguous continents. In a world like this it would be all about the boats. If going somewhere else meant going in a boat, there would only ever have been navies.

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    $\begingroup$ In a world like this seaplanes may also stay relevant for longer, given the difficulties in finding enough land (that isn't being used to farm or house people) to build long runways. And who's better to maintain a large number of seaplanes than the navy? $\endgroup$
    – Rob
    Commented Mar 22, 2021 at 13:00
  • $\begingroup$ This would work, but at the expense of the entire army branch becoming irrelevant. $\endgroup$
    – Alexander
    Commented Mar 22, 2021 at 16:19
  • $\begingroup$ Since this is tagged alternate history, it doesn't seem OP is looking for entirely-different-world-map levels of explanation... Also, these islands are very close together, so would a plane not be much more powerful (flexible) than a boat for warfare? $\endgroup$
    – R. Barrett
    Commented Mar 22, 2021 at 23:18
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    $\begingroup$ @Rob: your seaplanes already make sense because there is no need for runways to be built. If no island is larger than twenty miles across, then you are never farther away than ten miles from the biggest runway you could ever want. $\endgroup$ Commented Mar 23, 2021 at 6:55

There's one possibility, but let's explain why it's impossible first

About 1/3 of Earth's surface is land. Land has incredible advantages...

  • Fuel & maintenance delivery is cheap.
  • You can't sink a continent.
  • You're next to the manufacturers.
  • You're next to the training grounds.
  • Landing at night is nowhere near as big an issue.
  • Plane size is limited by the physics of the plane, not the physics of the ship.

And I could go on. Land has huge advantages when it comes to almost everything. On the other hand, your navy...

  • Has more trouble launching planes in bad weather than land-based operations ever would.
  • Must have raw material deliveries for fuel.
  • Is susceptible to torpedoes.
  • Is limited in the number of planes it can field (compared to comparatively infinite land).
  • Will always limit the size of the plane.

And, above all...

  • A navy is expensive. Really, really expensive.

If they must, planes can use a field to land and take off. Compare the cost of building an airport (about \$30 Million / 3km air strip) to the cost of the U.S.S. Gerald R. Ford (about \$12.8 Billion, ignoring the nearly \$5 billion research price tag).


Frankly, the economics of the issue alone kill the deal. Aircraft carriers would have to be cheap as proverbial water, which isn't believable. And that's ignoring all the other pros and cons. It's definitely useful to have a mobile air force (air craft carriers) such that one needn't negotiate landing privileges all over the globe — but it's a long way away from never having an independent air force.

Having said that... I did think of one possibility

Historically, small rockets (aka fireworks and limited munitions) came first, then airplanes, then big rockets (V1/V2, etc.). By the time ICBM missiles came along, the Air Force was already established and it made logical sense to put the two flying things together in the same military unit.

But let's keep in mind that the U.S. air force (to use as my test example) started as the Army Air Corps. If we assume that rockets came first and practical airplanes second, then we might have something. And I think that's a reasonable divergence from history (frankly, given that the Chinese were using rockets hundreds of years before the Wright Brothers, it's a wonder that practical rocketry didn't come first. The mathematics of ballistics aren't that difficult, but I'm sure Werner von Braun could give me a sound whoopin' over that calloused and uneducated statement.)

Anyway, practical rocketry would make a ton of sense in the navy. Think about it, the allies used battleships to soften the beaches at Normandy during WWII before the D-Day invasion. Practical rocketry would have provided (I believe) more payload over a longer distance, making that effort much more efficient. In fact, the navy would become the primary mid-to-long distance bombing solution rather than airplanes (which didn't come until later in this new timeline).

To be fair, this suggestion would be hard-pressed to overcome the other advantages of a land-based air force. But if we let that slide for a moment, there would never have been an Army Air Corps. It would have been the Navy Missile Service (NMS), and the burgeoning air force would have been absorbed into the navy, only receiving a separation (as it did with the Army) when intercontinental plane designs necessitated abandoning ship (think B-29 Superfortress and bigger).

I don't think it's possible to justify air support staying with the navy. In other words, it would eventually split into two services anyway. But by then the "Air Force" would be modeled after the navy, not the army.

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    $\begingroup$ I like the practical rocketry angle! Because after there are rockets there is rocket powered flying infantry and that is the dream we all dream of. $\endgroup$
    – Willk
    Commented Mar 22, 2021 at 0:57
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    $\begingroup$ Great answer! For what it's worth, ships firing rockets were actually used to bombard the beaches for the Normandy landings: en.wikipedia.org/wiki/Landing_Craft_Tank_(Rocket) $\endgroup$ Commented Mar 22, 2021 at 13:22
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    $\begingroup$ "You can't sink a continent." Is that a challenge? The Dutch have raised an entire province from the sea, watch us do the opposite if you make us angry enough. $\endgroup$
    – Mast
    Commented Mar 22, 2021 at 17:26
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    $\begingroup$ It might be interesting to note that the development of the ICBM program in America, the land-based launching silos, and the Strategic Air Command, almost completely devastated the American navy and rendered it essentially obsolete. Why do you need navy ships when the bomber and ICBM can get anywhere within hours? Ships are far too slow to fight in such a war, that would be over before a ship got anywhere near firing range. Until they developed ship and submarine based nuclear missiles, of course. With that, the American navy became relevant again. Ships could compete against bombers. $\endgroup$ Commented Mar 23, 2021 at 2:56
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    $\begingroup$ "Land has incredible advantages..." You missed the important part: we're land creatures. $\endgroup$
    – RonJohn
    Commented Mar 23, 2021 at 13:14

As in most things political, it comes down to the budget.

Those who control the purse strings, control who gets the money to spend on what.

Having more than one branch of the armed forces ALWAYS leads to increased military spending, as one branch tries to gain political power and influence over the other. A country that had every intention of keeping tight tabs on spending would have one budget line for all of the armed forces, and this budget line would be carefully controlled against redundant spending. One military branch, under which all forms of defense are centrally run and centrally budgeted for.

In point of fact, under the original American Constitution, there was only one national armed forces envisioned, and spending provided for, in the constitution, and that was the navy. Everything else, including the land armies, came after, post-constitution.


The basic requirement for a new branch of the military is that it can accomplish military objectives independently and in a new domain that is not covered by existing branches.

The US Navy (and I suspect others as well) already does have a huge air force. There is no sense in having the Air Force operate out of aircraft carriers, since those aircraft have the primary goal of winning naval engagements, so the Navy may as well take over there. Note that this is different even from the Marine Corps, which works closely with the Navy but handles marine engagements. They are not generally involved in naval battles.

In the land-based case, the Army's "air force" was originally used mostly for terror bombing and, more broadly, for attacking infastructure that the Army could not reach. It's primary goals where, therefore, separate from the Army's goal, and hence you get the Air Force breaking off from the Army while the Navy still has it's own "air force."

To finally answer your question, all you really would have needed to keep aircraft at sea exclusively is for the WW2 era terror bombings to be ineffective or illegal. There were actually discussions between representatives of the major powers in the 19th century about making terror bombings illegal on a moral basis, so the latter option is less implausible than it may seem at first. Moreover, prominent post-WWI military thinkers actually thought that terror bombing would be so effective that civilians would basically force their government's hand in surrendering almost immediately. This was, in fact, one of their moral justifications for the bombings (war would be brutal, but at least it would be short!). The fact that civilians could sustain years on end of bombing, sometimes while sustaining industrial output, was a big disappointment. I could have seen this leading to bombings to be outlawed as needlessly cruel for little effect. In the US, I think it's well known that the effectiveness of bombings in Vietnam were also a huge disappointment. Now that I think about it, it's sort of weird that such tactics didn't fall out of favor.

Anyway, if the Navy is the only branch with air power, I think you pretty much accomplish your goal. I know I didn't mention the Marine Corps but ... it's really hard to imagine nations not needing traditional land armies. For a lot of history, that's the only branch most nation's had.

Edit: You would very likely take interest in an episode of the Hardcore History podcast titled BLITZ Logical Insanity.

Edit 2: @RonJohn is contesting (in the comments) whether American's participated in terror bombings or only in precision raids. Rather than argue the point further, I will just point out that if you agree with @RonJohn, then you can swap out the Americans for the British in my example (as they point out) and my basic points still hold. The distinction between precision and terror bombings isn't actually that relevant to the question anyway.

  • $\begingroup$ The British air force was "originally used mostly for terror bombing" because they understood they couldn't hit a factory at night. The American air corps continued to try daylight precision raids throughout the war. $\endgroup$
    – RonJohn
    Commented Mar 23, 2021 at 13:13
  • $\begingroup$ @RonJohn Ostensibly we American's objected to terror bombing's and only hit military targets. On the official record, even the atomic bombs were precision attacks on military targets, but are we going to pretend the actual effects on the ground were unknown? There was no such thing as precision bombing in those days. $\endgroup$
    – user37344
    Commented Mar 23, 2021 at 14:46
  • $\begingroup$ We tried (as opposed to the UK). It's also why we've spent so many billions on precision munitions. $\endgroup$
    – RonJohn
    Commented Mar 23, 2021 at 14:50
  • $\begingroup$ @user37344 The Mosquito was used for a number of very successful precision bombing missions, and the precision involved in the Dambusters raid was phenomenal. As far as strategic bombing is concerned, one of the major challenges was simply navigating accurately to the correct target, in a world where radio navaids were in their infancy and the enemy was actively trying to deceive in terms of visual navigation. Forerunners of the ILS, VOR, DME and LORAN radio navaids (most still used today) were developed to help with that. $\endgroup$
    – Chromatix
    Commented Mar 23, 2021 at 19:05

I think you're starting from the wrong premise. It's not who is in control of the nascent space program or who is in control of which branch of the planet-bound military forces, it's the question of the environment.

So, TL;DR boils down to this: space force ends up organized as a navy because space.

Longer explanation is more fun, though. So here goes.

My contention is that space navy emerges more or less spontaneously because space is very similar to sea - unforgiving bitches both of them. To be able to operate in such hostile environment (yes, I mean it: you'd be surprised how many lives are lost at sea to simple bad luck, permanently crippling accidents not even mentioning, and both don't hold a candle to a fu**-up by someone in charge). This will almost by default produce an organization along the line of a navy. If you want, your space navy can have a wet navy roots and traditions, why not, but on the whole it's not necessary.

In addition to that, neither land forces nor (but to lesser degree) air forces have the tradition of independent command of a single large unit. Tank is 5 people, large cargo plane will have 5-6 people max... Mech infantry team will be 5 ppl fire team and a IFV, so say 7-8 soldiers. This is nothing compared to a destroyer with complement of 300+ and a vessel itself on the low end and 5000+ people on a carrier. No command structure of non-naval combat unit can accommodate that monster for the simple reason that while yes, there are lots of generals commanding larger divisions, not one is trained to be able to operate them as a single unit. Literally: army has it's Organizational and command structure to provide flexibility, while navy quite often need simple and brutally enforced blind obedience to orders for EVERYONE.

This lends itself to outsized marines force, but I think it's incorrect to think of them in terms of large tactical formations (divisions) as anything except administrative. For example, today's marines have multiple different duties, but on the whole largest force of them is distributed to the naval vessels (though not all) and installations (i.e. ports). Marines are responsible for internal security of a ship, often serve as an MP unit onboard (though it's not customary), will provide screening for landing parties, boarding parties, security for small crew detachments etc. They will also - because there are no idle hands on the cruise - they will be part of damage control, will have some watch duties as well. In other words: marines need to exist because their duties require specific training which, while not being truly multi-branch (army+navy+specops+aviation), are sitting on the intersection of them all. That is not to say marines should, ought nor be able to absorb army. Again: different use requires different tools. Army is quite often the sledge-hammer (by which I don't mean the attitude nor complexity nor the finesse in large-scale warfare) to marine's claw-hammer. Once warfare moves planet-side (if it's there in your world) it's entirely different beast.

My recommendation would be to simply ignore the emergence and treat is as a in-your-face-fact. No need to explain it, but if it's a part of the story, why not start with air force, then add navy officers as loaners to command space vessels and then it simply became obvious those traitors turned air force into navy. Add a funny twist that first it was submarine officers, but those bas___ds were REALLY crazy (sounds like a joke, but they REALLY, REALLY are sick moth______ers) and then they started using surface commanders.


I think for organic outgrowths, utility is a big part.

Imagine a shallow ocean world with large, shifting shoals. Or, a great deal of marshland, where paths shift in the sediment. Or even a world with large packs of constantly shifting sea ice where real-time information about passages is the only valuable information. In all of these cases, as soon as flight becomes available, it’s valuable to the navy.

In open water, a navy can use signal flags or lights to communicate and there’s nothing the enemy can do about it. But, in the more marshes universe, plant growth obscures line of sight communication. Aircraft re-enable communication for the navy that possesses these things.


Your question is a bit confusing. The explicit question is how to avoid air forces from becoming a separate branch. Based on the intro paragraphs, it seems like your real question is how to have navies in charge of space fleets. Those things aren't mutually exclusive.

You comment that air forces seem to be the ones building up military forces in space. That might be true now, but the space fleets you see in science fiction that are referred to as "navies" aren't remotely like what we're currently doing. Those space navies have capital ships, gigantic vessels with hundreds or thousands of crew members, multiple levels, hangar bays, etc. These capital ships go on missions for months or years at a time, with the ship becoming a mobile military base. They're essentially battleships and carriers that can fly.

If you're building a space armada, it makes far more sense to build it from your existing navy. Migrating to flying vessels is simply an incremental technology update. Basing your space armada off of your air force would mean that air force would have to re-invent most of what the navy already knows how to do and has a lot of experience doing. That's a lot of unnecessary work. Your air force will likely evolve into a local air defense squad. They'd continue doing what they're good at, and that's flying a variety of smaller, specialized craft with 1-2 man crews on short-duration missions. In a universe where interplanetary travel is common, that might be a small enough niche for the air force to get re-absorbed into the army and cease to exist as a separate entity.

All that is to say, you don't need a historic change to end up with navies controlling military forces in space. That appears to be the natural path that things would evolve (eventually).

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    $\begingroup$ America had to establish a completely independent 'Space Force' because the Air Force, Navy, and Army refused to co-operate on any kind of cost sharing or manpower allocation. So now the Space Force will develop its own naval, air force, and army assets. It's all about the 'chain of command' and resource allocation. $\endgroup$ Commented Mar 23, 2021 at 2:24
  • $\begingroup$ @JustinThymetheSecond And most importantly, about politics, and fighting over who gets to be in charge of stuff. Easy, cost-effective space travel will be such an extreme game changer that I expect you'll see a lot of consolidation and simplification between various branches, but that's still a long way off. $\endgroup$
    – bta
    Commented Mar 23, 2021 at 2:44

By chance, the navy got there first, and did such a great job changing things was unthinkable.

Perhaps in your world the navy was the first to equip and train military aviators - maybe the first wars of the age of flight were clearly naval matters, or float planes were very common, of the head of the navy had the foresight to see the importance of planes to the future of combat.

And in time they expanded to flying some planes from fixed bases - and to operations in support of the army.

Then the navy produced a bunch of decisive victories, the navy became national heroes and their leader became a household name. Perhaps the leading admiral had the stature of George Washington. Why take aviation away from the navy when it worked so well?

To someone in your world, that would be as absurd as splitting the army into the tank force and the infantry force.

Or alternately maybe the air force was on the wrong side of an internal power struggle and got disbanded or sidelined. Perhaps your fictional country had some equivalent to the soviet union's squabbles over power after the death of Stalin.

If your fictional country had a succession crisis/revolution/coup/attempted coup and the navy threw their lot in with the winning side, while the air force backed the losing side. The winning side naturally wanted to rid themselves of disloyal air force generals, so they gutted the air force's command structure and subsumed it into naval aviation.


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