 Wagner was a member of the "Naval Historical Team" based in Bremerhaven, which consisted of a group of German Naval officers appointed by the United States Navy to write down the war experiences of German naval forces from a German point of view in the conflict.The group produced a report in 1949 entitled "Soviet anti-submarine warfare potential (A historical summary of Soviet anti-submarine warfare (ASW) operations during World War II)", detailing missions of the German U-boats "U-9", "U-18", "U-19", "U-20", "U-23", "U-24", "U-576", "U-752", "U-986", and "U-997" in the years from 1942 to 1945.In 1951 via the Naval Historical Team Wagner authored a paper entitled "A Critique on Vice-Admiral Eberhard Weichold's essay on 'German surface ships—policy and operations in World War II'(promulgated in ONI GHS / 4)".