The new weapons that sprouted on the battlefields of World War I ultimately revolutionized warfare. At the time of their appearance, however, most of them were used in a very traditional way, making old-fashioned infantry and artillery more effective rather than ushering in new ways of fighting. Airplanes spotted targets for artillery batteries, scouted for the infantry and provided close air support. There were some attempts at strategic bombing, but due to the limited payload and range of the aircraft of the time, it had little effect. Tanks, which first appeared in 1917, operated with infantry units as moveable machine gun nests or bunkers.