Perhaps the most significant technological advance during World War I was the improvement of the machine gun, a weapon originally developed by an American, Hiram Maxim. They also developed air-cooled machine guns for airplanes and improved those used on the ground, making them lighter and easier to move. The planning and conduct of war in 1914 were crucially influenced by the invention of new weapons and the improvement of existing types since the Franco-German War of 1870–71. The chief developments of the intervening period had been the machine gun and the rapid-fire field artillery gun.