A flying ace or fighter ace is a military aviator credited with shooting down several enemy aircraft during aerial combat. The actual number of aerial victories required to officially qualify as an "ace" has varied, but is usually considered to be five or more. The few aces among combat aviators have historically accounted for the majority of air-to-air victories in military history.
World War I introduced the systematic use of true single-seat fighter aircraft, with enough speed and agility to catch and maintain contact with targets in the air, coupled with armament sufficiently powerful to destroy the targets. Aerial combat became a prominent feature with the Fokker Scourge, in the last half of 1915. This was also the beginning of a long-standing trend in warfare, showing statistically that approximately five percent of combat pilots account for the majority of air-to-air victories.
Use of the term "ace" to describe these pilots began in World War I, when French newspapers described Adolphe Pégoud, as l'As (French for "Ace") after he became the first pilot to down five German aircraft. The British initially used the term "star-turns" (a show business term), while the Germans described their elite fighter pilots as Überkanonen (which roughly translates to "top gun").
The successes of such German ace pilots as Max Immelmann and Oswald Boelcke were much publicised for the benefit of civilian morale, and the Pour le Mérite, Prussia’s highest award for gallantry, became part of the uniform of a leading German ace. In the Luftstreitkräfte the Pour le Mérite was nicknamed Der blaue Max/The Blue Max, after Max Immelmann, who was the first fighter pilot to receive this award. Initially, German aviators had to destroy eight Allied aircraft to receive this medal. As the war progressed, the qualifications for Pour le Mérite were raised, but successful German fighter pilots continued to be hailed as national heroes for the remainder of the war.
As the German fighter squadrons usually fought well within German lines, it was practicable to establish and maintain very strict guidelines for the official recognition of victory claims by German pilots. Shared victories were either credited to one of the pilots concerned or to the unit as a whole – the destruction of the aircraft had to be physically confirmed by locating its wreckage, or an independent witness to the destruction had to be found. Victories were also counted for aircraft forced down within German lines, as this usually resulted in the death or capture of the enemy aircrew.