New Guinea. Japanese consolidate their beachhead in the Gulf of Huon with landings at Finschhafen. In the morning, US Dauntless dive bombers and Devastator torpedo bombers fly 120 miles from American carriers USS Lexington and USS Yorktown in the Gulf of Papua, South of New Guinea, over the Owen Stanley mountains for a surprise raid on Japanese invasion fleet in the Gulf of Huon. They sink armed merchant cruiser Kongo Maru, auxiliary minelayer Ten'yo Maru and transport Yokohama Maru. Cruiser Yubari, destroyers Yunagi, Asanagi, Oite, Asakaze & Yakaze, minelayer Tsugaru, seaplane carrier Kiyokawa Maru, transport Kokai Maru and minesweeper No.2 Tama Maru (which sinks 3 days later) are damaged. 1 Dauntless is shot down by anti-aircraft fire. President Roosevelt tells Churchill it is "the best day's work we've had" but Japanese will send in their own aircraft carriers to protect against further US carrier strikes, leading to the Battle of Coral Sea.
Burma. Japanese 55th Infantry Division begins chasing the British retreat North from Rangoon. In their path lies Chinese 200th Division which took up positions on March 8 at Toungoo, 180 miles North of Rangoon.
In the middle of the Bay of Bengal 470 mile East of Madras, Japanese submarine I-62 sinks tiny British sailing ship Lakshmi Govinda with shellfire.
At 4.49 AM, U-161 approaches the harbor at Port Castries, St. Lucia, and sinks Canadian passenger ship SS Lady Nelson (25 killed, 204 survivors) and British freighter SS Umtata (4 killed, 169 survivors). SS Lady Nelson will be salvaged on April 16 and sent to Mobile, Alabama, to be converted to a hospital ship. SS Umtata will be salvaged on May 2 but sunk on July 7 while under tow to Port Everglades for permanent repairs by U-571 Northeast of Key West, Florida. At 6.32 AM 2 miles East of Barnegat, New Jersey, U-588 sinks US tanker Gulftrade carrying 80,000 barrels of bunker oil (18 drown in the oil slick, 16 survivors rescued by US net tender USS Larch and Coast Guard cutter USCGC Antietam). At 11.10 PM 400 miles Northeast of British Virgin Islands, Italian submarine Finzi sinks Norwegian MV Charles Racine. All 41 hands escape in 4 lifeboats (34 in 3 boats stayed together and picked up on March 12 by US destroyer USS Moffet, 7 in another lifeboat rescued by an Argentinean steamer).
Overnight, 62 RAF bombers, including Avro Manchesters of 106 Squadron, bomb Essen, Germany. They have slightly more success than the previous 2 nights, hitting railway lines near the Krupp factory (6 civilians killed, 12 injured).