Air to air combat, air to ground combat, heavier artillery and longer ranges with improved accuracy. Tanks. Dreadnoughts and U-boats.|||new weapons were made for combat. Like the tank for example, submarines, and machine guns. Plains were now made to fight in air warfare as well.|||Dont forget the chemical warfare with mustard gas.|||At first, huge zeppelins were used to spy on the enemy, to carry stuff around, etc. But then people discovered how easily they were shot down. So the airplane was used, for spying, at first. Then somebody dropped small bombs (grenades) on the enemy from above. Somebody else brought along a gun to shoot at other planes. A problem very quickly appeared: how to shoot at the enemy and not shoot off your propeller at the same time. The problem was resolved and the fighter plane was officially born.
At first, horses were used to carry and pull things around. But as the war went on, the gasoline/diesel engine replaced them. One very good thing resulted from this: before WW1, the United States did not have a very good road system nor did it have very good road maps. Europe did, and the guys from the States learned the value of a good road system by marching up and down France. When they got home, the official road building programs began in earnest.
