March 1: Bulgaria signs the Tripartite Pact, thus joining the Axis powers. - W47NV begins operations in Nashville, Tennessee, becoming the first FM radio station. - Arthur L. Bristol becomes Rear Admiral for the United States Navy's Support Force, Atlantic Fleet.

March 4: Operation Claymore - British Commandos carry out a successful raid on the Lofoten Islands off the north coast of Norway.

March 8: The U.S. Senate passes the Lend-Lease Act.

March 11: Franklin D. Roosevelt, President of the United States, signs the Lend-Lease Act into law, providing for the U.S. to provide Lend-Lease aid to the Allies.

March 15: Richard C. Hottelet is arrested by the Gestapo on "suspicion of espionage", but eventually released in July as part of a prisoner exchange.

March 16: A group of U.S. warships arrive in Auckland, New Zealand on a goodwill visit. On March 20, they arrive in Sydney, Australia.

March 17: In Washington, D.C., the National Gallery of Art is officially opened by President Franklin D. Roosevelt. - British Minister of Labour Ernest Bevin calls for women to fill vital jobs.

March 22: Washington state's Grand Coulee Dam begins to generate electricity.

March 24: Rommel launches his first offensive in Cyrenaica.

March 25: The Kingdom of Yugoslavia joins the Axis powers in Vienna.

March 27: Battle of Cape Matapan: Off the Peloponnesus coast in the Mediterranean, British naval forces defeat those of Italy, sinking 5 warships. Battle ends on March 29. - An anti-Axis coup d'état in Yugoslavia forces Prince Paul into exile; 17-year-old King Peter II assumes power. - Attack on Pearl Harbor: Japanese spy Takeo Yoshikawa arrives in Honolulu to study the Pacific Fleet at Pearl Harbor.

March 30: All German, Italian, and Danish ships anchored in United States waters are taken into "protective custody". - A German Lorenz cipher machine operator sends a 4,000-character message twice, allowing British mathematician Bill Tutte to decipher the machine's coding mechanism. (source: Wikipedia)