Born on 23 Jan 1919, Tiedemann was the Navigator of the B-24 “King Size, 42-50612, which took off from Hethel Airbase in England on a mission to bomb an industrial zone in Wahlen-Kall, Germany. After successfully dropping their bombs, the King Size was attacked by German fighters and went into a spin and started burning. This caused them to fall behind their formation, and they were attacked again and crashed. Of the crew of nine, only two survived. Tiedemann went down with the plane and perished in the crash.

Distinguished Service Cross Citation::
The President of the United States of America, authorized by Act of Congress July 9, 1918, takes pride in presenting the Distinguished Service Cross (Posthumously) to First Lieutenant (Air Corps) John Reeves Tiedemann, United States Army Air Forces, for extraordinary heroism in connection with military operations against an armed enemy while serving as Navigator of a B-24 Heavy Bomber in the 565th Bombardment Squadron, 389th Bombardment Group (H), EIGHTH Air Force, while participating in a bombing mission on 25 December 1944, against enemy targets in the European Theater of Operations. On this date, Lieutenant Tiedemann's aircraft was severely damaged and the bomb bay set on fire following repeated enemy fighter attacks. Two of his aircraft's engines were rendered inoperative, the control surface damaged and the main hydraulic system destroyed. In short time his aircraft became a lone straggler and was attacked by three enemy fighters who inflicted further damage and badly wounded several crew members. Realizing that the aircraft could maintain flight no longer, the Pilot ordered the crew to bail out and decided to attempt a crash in order that wounded crew members might be saved. Shortly thereafter, the aircraft exploded in mid-air and Lieutenant Tiedemann was not seen to leave it before hand. The extraordinary heroism and complete disregard for his personal safety displayed by Lieutenant Tiedemann on this occasion are in keeping with the highest traditions of the military service and reflect great credit upon himself, the 8th Air Force.