In January 1943, JANAC was formed by General George Marshall, the Chief of Staff of the U.S. Army, and Admiral Ernest J.
[1] The objectives of JANAC were as set forth in the following joint Army–Navy directive: By agreement between Chief of Staff and Commander-in-Chief, a Committee composed of 4 Navy and 3 Army members is appointed to meet from time to time at the call of the senior member to study and evaluate reports of loss or damage of enemy Naval and Merchant vessels from all causes, except those cases considered by the Anti-Submarine Warfare Assessment Committee of the Office of the Commander-in-Chief, U.S. Fleet.
At the end of World War II, Vice Admiral Charles A. Lockwood and his COMSUBPAC staff had estimated that approximately 4,000 ships had been sunk, totalling 10 million tons lost.
[4] JANAC estimates of Japanese losses revised wartime claims downward for most war patrols carried out by the submarine service during World War II as noted in the following table of the revised list of top ten submarines based upon the total tonnage sunk as determined by JANAC.
[10] JANAC also addressed wartime claims made by the U.S. Army Air Force regarding the sinking of the Japanese aircraft carriers Kaga, Akagi, Hiryū, and Sōryū during the Battle of Midway by giving sole credit to the U.S.