What would have been required for rockets to have dominated historically instead of cannons as the standard artillery weapon? There was enough of an overlap that this feels like it could have been possible.
A guidance system
The age of cannons is over. The age of RPG's, ICBM's and Air-to-air missiles is not. What caused this?
A cannon projectile is a stable system. Once launched from the muzzle of a gun, it's flight path is relatively predictable - it follows a parabolic arc. Sure, it's not 100% accurate due to tolerances between the bore and projectile, but it's not too bad.
A rocket is a much less stable system. If a rocket gets any angular velocity on launch could end up literally anywhere. It needs something to keep it straight. The simple solution are tail-fins. Tail fins are good, but if they are off by a degree or two you end up with rockets that fly in circles.
Rockets only really became useful after guidance systems were invented. Initially these just kept rockets on a straight line, but eventually they became active guidance systems using lasers, GPS, inertial measurement systems etc.
Once this point was hit, rockets became steerable explosive shells with longer range than cannons.
Ever notice there aren't any large bore guns on modern battleships? That's because a bunch of missiles is superior in every way except for cost. As a result battleships were largely replaced by guided missile destroyers.
What resulted in the development of guidance systems?
I suspect that rocket guidance systems largely evolved from torpedo guidance systems. Torpedos are slower and easier to control, and the first solution for guidance seems to have been in 1866 using ... clockwork and compressed air.
Could this have been developed sooner? Maybe.
What's next though?
Are cannon gone forever? Maybe not. Railguns allow much lighter-weight and cheaper ammunition, and can shoot at incredibly long ranges. I strongly suspect that guided railgun projectiles will be a major future long-range large-damage weapon.
I'll proffer an opinion; the factors that would need to be overcome historically are:
- Accuracy: unguided rocket artillery was and still is notoriously inaccurate. Against the close-packed troop formations of the era, the answer was to use them in large quantities to saturate the target area. However, for hitting individual targets at range, e.g. hitting a ship at a distance or hitting a fortification repeatedly in the same place to break it down, or even just hitting a specific part of a troop formation, that's not a workable strategy.
- Anti-fortification capabilities: early unguided rockets could deliver explosive warheads to do blast / shrapnel injury to troops, they could deliver incendiary to cause fires in settlements, but what they could not do is breach a fortification. A cannonball does damage to a fortification through sheer kinetic energy, cracking stone and timber. The rockets of the era can't build up the momentum (black powder as a propellant is only modestly powerful; one of the early rocket artillery experimenters successfully made 55-132 lb. rockets with casings made of wood (!)) to do much kinetic damage and uncontained detonation of a black powder warhead against a fortification wall would do little damage because of the low shattering power (brisance) of black powder.
- Cost : A cannonball is just a sphere of iron. The earliest practical artillery rockets, like the Congreve rocket, requires metal plate to be forged evenly, that metal to be painstakingly fabricated into a rocket, carefully packed with propellant, and a warhead with a fuze mechanism. All of this is very expensive given the level of metalworking and metal production available before the modern era. Additional complexity to make a rocket more accurate (e.g. the early spin-stabilized Hale rockets) or allow it to carry a bigger warhead would make it even more expensive.
lack of ability to move large objects/make large metal objects could cause cannon artillery to not be very popular, as a large block of heavy cast iron is very hard to move & make. With rockets the platform of launch can be a simple as a large frame as there is no need to contain a large instantaneous explosion or deal with recoil forces. It would even be possible to have a large formation of infantry with 1-3 rockets & a very simple frame to fire these rockets one at a time to not have to move any singular large object at all.
I'm assuming you mean "ball shaped cannon ball cannon" for this question.
First some background: We get conditioned with stories and media that fights were brutal affairs with every slash of a sword against the body killing someone and every cannon shot ripping through half a dozen bodies. In truth relatively few people died on the battlefield and most that did die would die from infection and disease after the battle.
When we hear of bayonet charges we picture people firing their last shots and then going on a stabbing spree. In reality bayonet charges almost always ended up with either party breaking up and falling back.
During the tail end of one of the world wars the British experimented with artillery barrages. Instead of the "standard" continuous barrage that could take minutes or hours, and occasionally days they would fire a short but heavy barrage. Then wait a set amount of minutes, then fire another short but heavy barrage. They found that after a continuous barrage most soldiers would still be around, but if they got plenty of clearly marked time to leave their defensive positions and get to safety they would.
The point here is that there are 3 rules that few people talk about in war:
- people don't want to die.
- (most) people don't want to kill
- people who think they are about to die are the most dangerous on any battlefield.
The point here is that psychological warfare is far more important than pure killing power. If you only bruise an enemy formation but scare the living daylights out of them and get them to retreat you are already closer to victory.
Mythbusters had remade one of the rocket artillery of the olden days. It used rockets to deliver arrows and wasn't about it's explosive power. The rocket arrows were decently accurate, loud and with nice smoke and flashes. They also fired several dozen of them in one go for the best effect. As a weapon of psychological warfare it was pretty much perfect.
You can add other limitations. Such as a lack of proper metal but plenty of materials to build rockets, or a society that had evolved it's rocket technology and industrial capacity for rockets so far that switching to canons was simply not that useful anymore.