Volume 19 of World War II Sea War provides additions and corrections to information already provided in Volumes 3, 4, and 5 for the period of March through December 1941. We also add general background data to help form the context of the war, especially how world leaders made decisions. The additions to Japanese data are extensive, providing information on Imperial Japanese Navy ship movements as Japan prepared to bring the United States into the war. This includes detailed information on Japanese conversion of merchant vessels for war time use and the movements and composition of Japanese invasion convoys. The additional data for December 1941 is actually larger than the original December 1941 data in Volume 5. The activities of the Royal Indian Navy and the Royal New Zealand Navy have been expanded. Some of the specific naval actions that have been enlarged include: ? Fleet Air Arm actions off Norway. ? Sinking of the BISMARCK. ? Battle for Crete ? German U-boat activity ? Naval events in the Arctic Ocean, Malaya, the Philippine Islands, the Gilbert Islands, Wake Island, and Pearl Harbor, Oahu.