The Pfalz Flugzeug Werke, located at Speyer am Rhein in Bavaria, was the third in the great triumvirate (along with Fokker and Albatros) of German fighter manufacturers in the Great War. When World War I broke out in 1914, Pfalz initially produced copies of the Morane-Saulnier parasol monoplanes for the German air service. With the advent of the famed Fokker Eindeckers with their synchronized machine guns, Pfalz entered the fighter market with the Pfalz E.I and its successors, all monoplanes which were similarly armed. Though never as as numerous as the Albatros or Fokker designs, the D III/IIIa was flown in combat by many well-known aces: Werner Voss, Carl Degelow, Erich Löwenhardt, and the balloon buster Fritz von Röth, among others. This book examines the little-known aircraft flown by these incredible men.