Why was the cannon so important in World War 1 and World War 2?

Answer 1

There were several reasons. Throughout history up until WWI, artillery was a "line of sight" weapon. The gunners had to be able to see what they were shooting at to be sure of doing much damage. They could fling heavy shells into a city under siege, as was done in the Civil War, if they did not particularly care what they hit, if anything. But by the time of the Civil War there were already artillery pieces which could fire accurately up to four miles or more, and that's getting to be pretty far for a line of sight weapon.

There were several developments before WWI, but probably the most important was battlefield communications. With the new field telephones, forward observers could communicate with the artillery behind the front lines, and adjust the fire, correcting the aim of the gunners and get their shells on target. Types of ammunition, fuses, explosives, all were much improved in WWI over what had been available previously. Hydraulic recoil mechanisms, pioneered by the French on their famous 75MM "rapid fire" cannon were a tremendous advance. In earlier wars after each discharge of the gun it had to be wrestled back "into battery", into proper position to fire the next shot, by the gun crew, by hand. The guns could weigh a ton, so this was not easy. With hydraulic recoil mechanisms the gun remained stationary. The French "75" with a well trained crew could have seven more shells in the air, on the way, by the time the first one hit the target. The Industrial Revolution was far advanced and meant that there were factories capable of producing modern cannon and mountains of ammunition for them. Aircraft could be used to spot targets and to send message, by wireless telegraph, to correct aim.

By WWII there were voice radios, allowing even better fire control by forward observers with the front-line troops. Voice radio-equipped aircraft were better for spotting targets and adjusting fire. There was better coordination between air controllers and ground troops. The Field Artillery branch of the US Army was the best of the US combat arms in WWII. We had the capability of drenching a target with preparatory fire before an attack, and of calling in artillery fire from batteries "on call" to take such missions to break up enemy attacks. The US infantry divisions of WWII were actually pretty short on rifle strength, but had a tremendous organic artillery component, with three battalions of 105MM howitzers and one battalion of 155MM howitzers. Additionally, each of the three regiments in an infantry division had a cannon company. On top of these there were hundreds of "independent" battalions, not a part of any division, assigned to a corps or army HQ, of artillery of various calibers, called the "corps artillery" or "army artillery" for additional firepower. Our enemies were jealous of all these barrels available and the lavish supplies of ammunition for them (and half of all artillery ammunition manufactured during the war never even made it overseas). The Germans had some excellent artillery, particularly their famed "88", but the ammunition was often short.

US gunners had also developed a particularly devastating tactic just before WWII, still used today, called "Time On Target" (TOT). Using this, mathematics were used to calculate so that every gun within range of a given target could fire so that ALL their shells arrived on the target at the same instant. Very devastating and VERY demoralizing to enemy troops on the receiving end.

A great secret weapon of the war was the "proximity fuse". This was an artillery fuse which was actually a tiny radar set in the nose of the artillery shell. Shooting anti-aircraft artillery at enemy planes had been a matter of estimation and luck before - of altitude, speed and distance to target, so the fuses could be set to explode, it was hoped, near the planes. Now all that had to be done was fire so that the shell passed close to the enemy plane, and the proximity fuse would detonate the shell when close enough to destroy the plane. At first these were used only by the US Navy and only when in deep water, so there would be absolutely no possibility of the enemy recovering an unexploded shell equipped with a proximity fuse and learning its secrets. This was the reason for the devastating effectiveness of anti-aircraft gunnery against the Japanese in the Pacific. By late in the war though the proximity fuse was cleared for use by the field artillery of the army, where it could be used to produce air bursts over enemy troops dug in, in fox holes or trenches, and rain shrapnel down on them.