Merchant shipping losses according to the U.S. Joint Intelligence Committee. Daily summary dated 20 December 1941

An item rereferred to Admiralty London dated 11 December reporting the shipping losses for November amounted 100,491 tons included 88,000 tons of the British. Losses nearly 100,000 tons lower than October 1941 and except for the month March the lowest monthly losses since the war broke out.

Source

Map Room Papers (Roosevelt Administration), 1942 - 1945. U.S. Joint Intelligence Committee. Daily summary No. 10 dated 20 December 1941.