On this day, U.S. and Australian land-based planes begin an offensive against a convoy of Japanese ships in the Bismarck Sea, in the western Pacific.
On March 1, U.S. reconnaissance planes spotted 16 Japanese ships en route to Lae and Salamaua in New Guinea. The Japanese were attempting to keep from losing the island and their garrisons there by sending 7,000 reinforcements and aircraft fuel and supplies. But a U.S. bombing campaign, beginning March 2 and lasting until the March 4, consisting of 137 American bombers supported by U.S. and Australian fighters, destroyed eight Japanese troop transports and four Japanese destroyers. More than 3,000 Japanese troops and sailors drowned as a consequence, and the supplies sunk with their ships. Of 150 Japanese fighter planes that attempted to engage the American bombers, 102 were shot down. It was an utter disaster for the Japanese--the U.S. 5th Air Force and the Royal Australian Air Force dropped a total of 213 tons of bombs on the Japanese convoy.
British Prime Minister Winston Churchill chose March 4, the official end of the battle, to congratulate President Franklin D. Roosevelt, since that day was also the 10th anniversary of the president's first inauguration. "Accept my warmest congratulations on your brilliant victory in the Pacific, which fitly salutes the end of your first 10 years."