The world has a Plot Device Treaty which, being a Plot Device, bans aircraft from being effective against ships.

As we have seen from history, such treaties are often violated, circumvented, or otherwise rendered ineffective.

I need a plausible reason for countries to be uninterested in bypassing this treaty. Especially since, at some point, someone will realize just how powerful and cost-effective aircraft can be.

The time period that this Plot Device Treaty is written in is similar to the 1920s - Early aircraft, with some visionaries but many who are disdainful and actively trying to undermine it. Many of them have political power after the Big War, so passing the Plot Device Treaty isn't an issue. The time the story is set in is equivalent to the 1950s in technology, so it's 20-30 years that this treaty has been in effect. It doesn't need to be enforced much longer, as Big Things happen in the story that render the Treaty largely irrelevant.

With multiple nations involved (Some of which really dislike each other) and at least one significant (Perhaps world-spanning, perhaps not. Haven't decided) war, how would the countries be enticed to follow the treaty?

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    $\begingroup$ "Uninterested in bypassing this treaty" is a tricky wording. As a general rule, treaties are written because someone was interested in doing something and the treaty was negotiated to stop them. A minor wording shift may help spawn creative solutions: I think you want your countries to be interested in supporting this treaty, and you want that interest to be strong enough to overwhelm the interest in bypassing it. Thinking in positive terms rather than negative ones can help open up new solutions. $\endgroup$ – Cort Ammon Dec 15 '17 at 14:55
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    $\begingroup$ Rather like chemical weapons, the deterrent to one side breaking it is the knowledge that the other side will do so as well. $\endgroup$ – pjc50 Dec 15 '17 at 16:38
  • $\begingroup$ How can you make an aircraft ineffective against a ship? Same bomber can be used against land and sea targets. You may ban aircraft carriers, that would be interesting. $\endgroup$ – Alexander Dec 15 '17 at 18:11
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    $\begingroup$ @pjc50, the concept of "mutually assured destruction" only works if both sides have a lot of the affected resource (in this case, airplanes taking the place of nuclear missles) such that a preemptive strike has little value. Chemical weapons during WWII "enjoyed" the same status (either stockpiled from WWI or very easily manufactured). OP, is this the case? Does your world have enough planes for MAD to be effective? $\endgroup$ – JBH Dec 15 '17 at 18:30
  • $\begingroup$ @alexander By banning bombs, rockets, and missiles. It's explained in my other question $\endgroup$ – Andon Dec 15 '17 at 19:22

13 Answers 13


If you replace in your story the "airplanes" with "nukes" you have pretty much what happened with nuclear weapons.

The various treaties signed over the years have been observed thanks to:

  • mutual surveillance: each superpower could check that the terms of the treaty were being observed by the others
  • a third party agency monitoring
  • political willingness from all the involved parties

Yes, there have been nations not observing or even signing the treaties, but I think you also want those elements in your plot.

On the other side, airplanes are far from being as lethal as nukes. You can hardly set up MAD (mutual assured destruction) just because you have airplanes... You probably need to tweak a bit on the reasons behind why there is such a vast consensus over banning airplanes.

  • $\begingroup$ Nukes came to mind, but... then they're nukes and MAD is a significant thing. Following those treaties does gain some political nice feelings, which can be useful. $\endgroup$ – Andon Dec 15 '17 at 6:48
  • $\begingroup$ There were thinkers at the turn of the 19/20 centuries who thought that the discovery of aircraft would set up MAD and make wars impossible. $\endgroup$ – vsz Dec 15 '17 at 12:30
  • $\begingroup$ @vsz, earlier they thought the same of machineguns... $\endgroup$ – L.Dutch - Reinstate Monica Dec 15 '17 at 13:14
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    $\begingroup$ @L.Dutch : Both were right on one thing: it did make Napoleonic-style, closed-formation warfare impossible. But humans are creative in finding alternatives... $\endgroup$ – vsz Dec 15 '17 at 14:12
  • $\begingroup$ Rep for pointing out that planes are not nukes. The consequence of nukes is so terrible that the civilian population would do almost anything short of losing a war to avoid them. I'm not sure planes dropping conventional explosives can reach that level of civilian lethality. However, carpet bombing was pretty ugly.... $\endgroup$ – JBH Dec 15 '17 at 18:35

Such treaties are often accepted and upheld, because the consequences of not upholding them are terrible for everyone involved. Weapons of mass destruction are the typical example of this, but the general principle holds for other things. Thus, I propose that you find a reason why, in your world, it is really important not to hunt down ships.

Maybe ships are also built from hard to replace resources. Maybe the layout of your world makes naval transport really common and integral to the functioning of society. This would be especially true if many countries depended on sea access for basic goods such as food, fabrics, fuel and similar things. Goods whose loss will severely impact the civilian population of every country, leading to the deaths of thousands of innocents through starvation, freezing etc, thereby also crippling wartime production but doing so with a huge price. Then, make sure that this weakness holds true for all relevant nations (possibly with different goods for each), so that if one country starts sinking ships with planes, every country can do so and everyone suffers more than they are willing and/or able to bear.

  • $\begingroup$ The food situation on this planet isn't the best - Humans can't just go eat things, it has to be farmed and often processed. Early days on this plant were pretty low-tech, so the easiest methods to move things was via water. So, there are lots of ships moving food around. On the other hand, a sufficiently powerful nation might believe they can protect their own stuff perfectly well (Regardless of if they actually can or not) $\endgroup$ – Andon Dec 18 '17 at 1:18

Chemical weapons in WWII. Both sides had them, both knew that the enemy had them as well, but the balance of terror held.

  • This assumes all sides have plot device capable aircraft, and there might be episodes like civil wars or suppression of revolutions where they are used.
  • Military planners would be aware that the enemy might deploy plot devices when push comes to shove, so they'd have to think about countermeasures. They'd be aware that those countermeasures will fall short, so the balance of terror holds.

Strong neutrals who push for the treaty. A bit like the right of neutrals to trade with belligerents during early WWI.

  • The right to sail merchants through a blockade is something understandable to the man in the street. The right that one foreign country doesn't bomb another foreign country is harder to grasp in those terms.
  • It might help if the neutral power is truly neutral and if it does not want the outright victory of one of the belligerents. Their preference would be that they exhaust each other.

While nations are at peace and trading with each other, nobody has any particular vested interest in breaching the treaty. It's only once war starts that it will rapidly start to fall apart.

Either the war is rapidly won, or such treaties become casualties. Operations like Ministry of Ungentlemanly Warfare will be set up and one of the things they'll look at is a way round such a treaty.

Victor's justice, assuming the nation that broke the treaty is victorious, will mean that the treaty is just another casualty of war, along with the other various trade and peace treaties that existed before the war broke out.


The Big War was shorter than the Great War or World War I. Too short for aircraft to be proven as effective weapons of war.

Originally, aircraft, which included observation balloons, were mainly used as reconnaissance vehicles to determine enemy positions, troop concentrations, military facilities, and artillery emplacements. It took time for them to be used as fighting machines. This suggests if the Big War was over faster then the effective military development of aircraft might be missed.

Alternatively, this was a world where the development of aircraft was either slower and hadn't progressed as far when the Big War broke out. This could mean aircraft had to undergo much more development and innovation than in our reality.

A major factor in a quicker version of the Big War could be that world's equivalent of Germany failed to invent the Haber process. Germany was on the verge of running out nitrates for the use in their munitions (artillery shells, bullets and explosives). Nitrates were mainly imported into Germany. The Haber process enabled the synthetic production of nitrates, thus prolonging World War I.

During World War I, the production of munitions required large amounts of nitrate. The Allies had access to large sodium nitrate deposits in Chile (Chile saltpetre) controlled by British companies. Germany had no such resources, so the Haber process proved essential to the German war effort.[9][11] Synthetic ammonia from the Haber process was used for the production of nitric acid, a precursor to the nitrates used in explosives.

A combination of all the above suggestions could result in a situation where military aircraft weren't sufficiently developed to be a threat, but their potential may have been becoming obvious. Therefore, a Treaty to ban their use would be likely to be passed and its enforcement would be easy. No-one fully realized the potential of air warfare and believed they could do without the cost of the research and development. This, of course, would be a world without air travel.


The simplest answer is that there are two large powers who are:

  • Neither friendly nor particularly unfriendly towards each other (think late '90s China vs USA)
  • Reliant on naval power (both civil and military)

Both have a good reason to limit the development of anything that makes ships vulnerable, and the power (economic, diplomatic and military) to keep the Status Quo. Neither power will want to risk developing the devices themselves, as this will likely erode their power relative to smaller nations in time to a sufficient degree to make their temporary advantage over the other power un-worthwhile. No smaller power can risk the wrath of the two larger powers.

Then have the treaty enforced by inspections, etc and off you go. The chances are though that such things will fall by the wayside on day 1 of a major war - but there is a reasonable chance that if the treaty has been successful, that development will be at a very basic stage when things kick off.


States obey treaties that are in their best interest. Period.

States choose to obey their agreements (treaties) simply because the rulers believe that it is to their advantage to do so. A corollary is that States are likely to promptly break or violate agreements if they believe that greater advantage will accrue.

'Advantage' can be political, military, financial, personal, etc. Often it's more than one. And that's your opening as an author. When looking at treaties, it often helps to look through the lens of Advantage. There is often prestige and strategy involved...and occasionally corruption, too. It's a rich tapestry.

Successful treaties since 1945 tend to include:

  • Multilateral institutions to transparently handle inspections, to reduce espionage, and to prevent secret abrogation
  • Clear designation of accountability for overseeing execution of the treaty, like the UN Security Council or the International Criminal Court
  • Specified methods of resolving disputes like multi-party talks, sanctions, referrals to UNSC or ICC, etc

Just like earlier treaties, States participate when they feel that it in their best interest to do so. And states will drop out when they feel it is not.

The post-1945 additions do two relevant things here: They push the development of international institutions as important and relatively impartial players, and they discourage states from cheating or dropping out by clearly expressing the consequences to their Advantage.

One example of a successful multilateral treaty is the Vienna Convention of 2009, which is allowing the Ozone layer to regenerate.

However, a more instructive example of a less effective treaty may be the Washington Naval Treaty of 1922, which briefly limited the construction of large warships.

  • Many were interested in reducing costs due to the post WWI recession
  • Competing interests and jockeying for advantage scuttled the proposed prohibition of submarines
  • Japan was willing to accept lower numbers because it had greater concentration than it's more industrialized competitors
  • It unexpectedly caused a building boom in some types of ships
  • There was no inspection nor enforcement mechanism, making failure of the Treaty likely after a few years. Sure enough, the treaty lasted less only a decade

The upshot: If you really want to ban aerial bombing before 1945, you have the League of Nations available to carry out the institutional roles. You can crib consequences and sanctions from current arms control treaties. You can justify initial Advantage for a different reason in each country: A recession, a currency collapse, a failed coup, fear of a more technologically advanced neighbor, war exhaustion, and many more.


A lot of other answers are correct in saying that retaliation is the primary motivation for using prohibited weaponry such as chemical or nuclear weapons. However, in order for this to be true, there must also be few, if any, effective countermeasures to such weaponry.

Chemical weapons are avoided because you can't really defend against them effectively. So although they might be effective against your enemy, they will be equally as effective against you.

Nuclear weapons are avoided because missile defense systems are pretty dodgy and you can't rely on them. If it was possible to effectively defend against nuclear missiles, their use would be much more likely. Cold War actors recognized this early on and 1972 the US and USSR signed the Anti-Balistic Missile Treaty which limited the scope of each nation's missile defense systems.

However, in your example of limiting the effectiveness of aircraft against ships, I doubt that no nation would be unable to develop countermeasures against aircraft. Anti-aircraft guns are simple to make and bullets are cheap. Ships equipped with anti-aircraft gunners could easily provide a defensive screen for a nation's ships that could limit damage. Although opponents would also have anti-aircraft guns, I could see a nation deciding the potential benefits outweighing the risks and believing that they could increase their effectiveness through better training and/or tactics.

In order to entice nations to follow the treaty, you want to throw off this cost-benefit analysis so that breaking it by using aircraft against ships is simply not worth it. One way I think you could do this is by decreasing air density (or increasing temperature, see this answer on the Aviation SE). Decreasing air density or air temperature will make it harder for planes to take off, requiring either longer runways or redesigning planes. While longer runways is easy enough on land, it isn't really feasible for launching off ships: a longer runway means a bigger ship which means a bigger and more expensive target. Since aircraft carriers are often the most expensive and heavily crewed ships in a fleet, nations may want to avoid building them altogether. Even using steam catapults would be hard, as they'd need to be more powerful and they are already extremely heavy and dangerous equipment on board ships.

An alternative of course is to redesign your planes, you could make wings larger, which means more lift but it also means they take up much more space on board your aircraft carrier which means you can't carry as many planes, once again limiting their effectiveness. It could also mean lighter aircraft by carrying fewer explosives, which would of course limit their effectiveness against ships to begin with.

I'm not sure how much less dense air would have to be in order for this to be effective and there may be other side effects I'm not thinking of here, but that's out of scope for this question.

Edit: I forgot something else! A thinner atmosphere would also force planes to fly at a lower altitude, making it easier to hit them with anti-aircraft weapons.


Because using them causes Very Bad Things(tm) to happen

All the other banned weapons have this one trait. Chemical warfare is banned because it is indiscriminate, causes mass death, even on both sides, can't be protected against and destroys everything it touches.

Nuclear weapons are the same plus extra world ending sprinkles on top.

Logically it makes no sense to ban the use of aircraft to sink ships if ships can also sink ships. Both result in a sunk ship. The main difference between aircraft and other ships is where they operate : the sky.

Ships also operate on the open ocean, where as other forms of warfare happen on land. Thus for a very specific treaty like this, you need something bad to happen when aircraft operate on the open ocean.

For the time period you have mentioned, aircraft were not yet capable of high altitude warfare with naval ships, they needed to be fairly low to hit them with anything. So we could limit this to low altitude aircraft over the open ocean, so that passenger aircraft and air to air combat is still viable.

For an example, we could imagine a very populous migratory bird that traverses the open ocean continuously and goes to the continental mainlands around the world at certain times for breeding or whatever. They are highly tuned to see objects at their flying altitude and follow them in big chains of migrating birds. When aircraft fly near these altitudes the birds become confused and huge swathes of them die from going off course and never reaching land.

The impact of this happening after the first few occurrences begins to show itself as significant portions of the ecosystems worldwide go haywire and entire crops and other species start to die off because the magical ocean minerals the bird poo provides the soils aren't present.

A treaty is created that forbids low altitude aircraft over any portion of the ocean more than 5 miles from the coastline. Provisions are put in place that forbids weapons development for aircraft to target naval ships so nations aren't enticed to try to use them anyways.

Later on maybe research finds that aircraft created in certain shapes or colors don't trigger this effect, or high altitude bombing becomes a thing.

There are other situations that could prove highly damaging that would cause a treaty like that to be signed but it needs a component that makes not adhering to the treaty very dangerous for everyone.


As answered have said - there needs to be a deterrent to ensure treaties are enforced. But you don't need to revert to pre-treaty days against an adversary who breaks them. eg. Dropping chemical weapons on an adversary who has started to use them.

Instead you hit them with other deterrents, such as trade embargoes or asset freezes. A country unable to trade with anyone else is either so powerful they can do what they like anyway, or will quickly crumble and end up as a feeble dictatorship followed by collapse, and either way the rulers will not be able to get and enjoy their riches as they otherwise would.

I think most treaties have punishments either written into them, or the organisation managing them has deterrent powers to bring to bear, with the means to force other treaty signatories to be involved in enforcing the deterrent. In these cases, a lot of countries would find it in their interests to damage the offending country - to steal their trade or seize their assets for example.


I don't know how similar or different your world is.

One way to make such a prohibition is for every major power to be heavily invested in civilian merchant ships, and naval ships of all types up to battleships.

Possibly the major powers have so much capital invested in shipping that is expected, unlike most ships in our world, to last for decades into the future, that several forms of sinking civilian and naval vessels have been banned such as mines, submarines, and airplanes.

Another way is to make airplanes banned as weapons of war. The first major uses of airships and airplanes have been as terror weapons, and so all use of warplanes is abhorred and prohibited. The leaders of the first nations to use airplanes in war have been executed for so doing, setting a legal precedent. Or maybe the officers and men who carried out those missions have all been executed, making all future soldiers reluctant to obey such orders.

A third possibility. Maybe petroleum based fuels and internal combustion engines have been introduced much later in your world. A decent merchant marine and battleship navy can be propelled by steam engines and coal, while coal and steam powered airplanes would be every inefficient.

A fourth possibility. Maybe in your world a nation's airspace only extends to the height of a skyscraper above the ground and the air above that is considered to belong to everyone like the open oceans. And maybe in your world flying is considered to be a glorious and sacred activity and it is considered sacrilegious to defile flying with commercial or military use.

A fifth possibility. Maybe after the last big war where a lot of new weapons were introduced treaties were signed forbidding the use of ANY technological innovations in war, not just airplanes. Possibly the victorious nations feared that technological innovations could favor their rivals, while the war weary populations of the losing nations blamed new technologies for ever increasing devastation and death tolls of wars and demanded a halt to the development of new weapons.

Possibly some combination of some of those five suggestions would suffice to explain the non use of airplanes against ships in your world.

  • $\begingroup$ Most of these don't fly (Hah!) in this world, but a lot of thigs to think over. Especially the semi-religious aspect. $\endgroup$ – Andon Dec 16 '17 at 14:31

Economic consequences for violating the treaty seem like a good motivation. There could be also a organisation like the UN ... Or maybe you send agents to the weapon factory's to make sure these facilities follow their orders. 🤔


We're looking for long answers that provide some explanation and context. Don't just give a one-line answer; explain why your answer is right, ideally with citations. Answers that don't include explanations may be removed.

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    $\begingroup$ I feel that this does provide an answer, but that it is very short on details. It seems like a pretty good starting point, though. Coolconcrete, can you Edit to expand on how this would work, the consequences for still violating the treaty, etc.? Longer answers with some analysis of the idea(s) presented are typically better received by the community. $\endgroup$ – a CVn Dec 15 '17 at 8:23

As many of the answers have said, you're going to struggle to convince a nation; a power not to abuse a treaty for an easy win.

I would advise against the planes are like nukes mentality as it doesn't really make sense. The total destruction of civilian centres is just not the same as sinking an enemy ship - it never will be to your audience either. However there is a somewhat simpler way (depending on how much control you have over histroy):

Let's say that the countries involved in this war are all either Phristian or Pewish (no offense intended on either). The religious backgrounds hold a similar thread up to a point. As it happens one of the tales of old is how Abraham sought to call down God's wrath on his enemies - destroying their boats from the air using gliders deployed from nearby mountains (this was plausible with 500AD tech). But God was displeased with Abraham; God and God alone may rain hell fire down from the heavens, Abraham was punished by God etc., Skip forward 2000 years and everyone knows you don't rain hellfire or God will rain it on you. It's not quite a commandment, but it's certainly not the Phristian thing to do. The people would be appalled if their government decided to go against the moral will of the country for something as petty as a boat.

With a little writers poetic license and something a bit more buzzy than you don't rain hellfire or God will rain it on you, you could make upholding the treaty be a move based on national (not international) politics.


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