The earliest military aircraft were used primarily in a reconnaissance role. In 1915, during World War I, aircraft designer Anthony Fokker developed a gear system that allowed a plane-mounted machine gun to fire through the propeller, giving birth to the first fighter aircraft. The fighter's mission was to shoot down enemy reconnaissance and fighter planes. Later, as the use of bombers became more widespread, fighters were called upon to act as interceptors against enemy bombing runs and escorts for friendly bombers. The best way to ensure the safe passage of friendly bombers to their selected targets is the destruction of enemy fighters.