The science and technology needed to fly an airplane were developed just a decade before World War I, but it didn't take long for planes to find a military use. Both sides of the conflict used planes to spy on the enemy, drop bombs, and fight other planes in midair with mounted machine guns. Military aircraft became more powerful and sophisticated between the two world wars.

There were limitations to the early airplanes, however, since they couldn't fly very fast or maneuver very quickly. The next development was the jet engine, which could push a plane forward at speeds faster than sound.

Building on previous discoveries, engineers in Britain and Germany independently discovered ways to outfit aircraft with jet engines. These new planes were much more powerful than existing aircraft. The few jet-powered military planes of World War II were built toward the end of the war, so they had little military impact, but by 1950 jet engines were the primary method of powering fighter planes. Throughout the Cold War, aerial battles (known as dogfights) took place between the superpowers' jet fighters.

It was the competitive drive of war that urged engineers to make faster, more powerful aircraft. The planes we fly today use more advanced versions of the jet engine technology that was developed during World War II.

Which of the planes pictured below was flown during World War I, and which was flown during World War II? Think about your answer and then click on each image for an explanation.