Tanks and aircraft captured the imagination, but artillery killed more soldiers than every other weapon combined. The revolution in gunnery—predicted fire, sound ranging, counter-battery work—was how the trenches were actually overcome.
Before the proximity fuze, anti-aircraft shells had to score direct hits on fast-moving planes. After it, they just had to get close. This tiny radio device may have killed more enemy aircraft than any other weapon—and it was kept so secret that soldiers weren't told how it worked.