Original: Use of the term ace in military aviation circles began in World War I (1914 - 18), when French newspapers described Adolphe Pegoud, as l'as (French for "the ace") after he became the first pilot to down five German aircraft.
Simplified: Use of the term "ace" in military aviation began in World War I (1914 - 18). French newspapers called Adolphe Pegoud, as l'as (French for "ace") after he became the first pilot to shoot down five German aircraft.