World War II gave rise to even more technology. The worth of the aircraft carrier was proved in the battles between the United States and Japan like the Battle of Midway. Radar was independently invented by the Allies and Axis powers. It used radio waves to detect objects. Molotov cocktails were invented by General Franco in the Spanish Civil War, directing the Nationalists to use them against Soviet tanks in the assault on Toledo. The atomic bomb was developed by the Manhattan Project and dropped on Hiroshima and Nagasaki in 1945, quickly ending World War II.