The 103rd Aero Squadron was an aviation pursuit squadron of the U.S. Air Service that served in combat in France during World War I. Its original complement included pilots from the disbanded Lafayette Escadrille and Lafayette Flying Corps. One of those pilots, Paul F. Baer, became the 1st Ace of an American unit in World War I.

The 103rd Aero Squadron was the first U.S pursuit squadron in action during World War I and had the longest combat service, from 18 February to 11 November 1918. It flew 470 combat missions, engaged in 327 combats, destroyed 45 German aircraft in aerial combat and claimed an additional 40 as probably destroyed, shot down two balloons, flew 3,075 hours over the front lines, and dropped 4,620 pounds of bombs. It's casualties were 5 killed in action, 2 killed in flying accidents, 4 prisoners of war, 3 wounded in action, and 1 injured in a forced landing.

The commander of the 1st Pursuit Wing, in general orders, said of the 103rd:

"In February last the Lafayette Escadrille of the French Army was transfered to the 103rd Aero Squadron, United States Army. It was the first, and for nearly two months it was the only American Air Service organization on the front. Since that time it is not to much to say that the pilots who served in the squadron have formed the backbone of American Pursuit Aviation on the front . . . No task was too arduous or too hazardous for it to perform successfully. In the recent decisive operations of the First American Army the 103rd Aero Squadron has done its share." Lt. Col. Burt M. Atkinson, 16 November 1918