S/Sgt John P. O'Brien flew 27 missions, from 03/02/1944, mission #29, to 07/25/1944, mission #116. He served as a Ball Turret Gunner and Left Waist Gunner.
S/Sgt O'Brien served with the following crewman: Sgt James E. Bachler, Sgt James R. Baehler, 2nd Lt Harold W. Dershimer, S/Sgt Elmer M. Fetzer, 2nd Lt Dene C. Gober, T/Sgt Cecil B. Greer, 2nd Lt Wardlaw M. Hammond, 2nd Lt James J. Hannon, 1st Lt Lewis S. Jaffe, 2nd Lt George R. Lewis, 2nd Lt Alexander R. Livingstone, S/Sgt Alexander M. Martinelli, T/Sgt Elmer C. Munch, 2nd Lt Edward T. O'Neill, T/Sgt Maurice C. Priest, T/Sgt Thomas Urnson and 2nd Lt Myrick J. Whiting