The 1st Pursuit Group claimed more enemy kills than any other Group in the United States Air Service in World War I, partly thanks to 'ace of aces', Eddie Rickenbacker, and balloon-busting ace, Frank Luke, both of whom also earned the Medal of Honor. Starting operations in March 1918, the Group initially flew Nieuport 28s, now rejected by the French, and quickly showed its quality. Douglas Campbell was the first American-trained pilot in the USAS to make a kill and soon afterwards became theService's first ace. Expanded by the arrival of additional squadrons, the Group went to war in earnest over Ch_teau Thierry in July, suffering heavy losses against experienced German pilots and better airplanes. Re-equipped with the superior Spad XIII, the now battle-seasoned Group achieved its full potential over St. Mihiel and the Argonne. This is the story of the Group that produced some of America's first fighter aces and its rapid evolution over a few months as a deadly rival to opposing German units with years of combat experience behind them. Its publication marks the 90th anniversary of 1st Pursuit Group's distinguished contribution to Allied victory.