Hamilton Coolidge was born on September 1, 1895, in Brookline, Massachusetts. He enlisted in the Aviation Section of the U.S. Army Signal Corps in July 1916, and began flight training at the School of Military Aeronautics at the Massachusetts Institute of Technology in June 1917. Coolidge sailed to France in July 1917, and was commissioned a 1st Lt on September 29, 1917. Lt Coolidge was assigned to the Third Aviation Instruction Center at Issoudun, France, from October 1917 to June 1918, and then joined the 94th Aero Squadron of the 1st Pursuit Group. He was credited with the destruction of 9 enemy aircraft in aerial combat before he was killed in action on October 27, 1918.

His Distinguished Service Cross Citation reads:

The Distinguished Service Cross is presented to Hamilton Coolidge, Captain (Air Service), U.S. Army, for extraordinary heroism in action near Grand Pre, France, October 27, 1918. Leading a protection patrol, Captain Coolidge went to the assistance of two observation planes which were being attacked by six German machines. Observing this maneuver, the enemy sent up a terrific barrage from anti-aircraft guns on the ground. Disregarding the extreme danger, he dived straight into the barrage, and his plane was struck and sent down in flames.