In April 1941 Adolf Hitler assured Japan he would fight the United States if Japan were to attack the U.S., setting the stage for Pearl Harbor eight months later. The World War II timeline below summarizes this and other important events of World War II.
World War II Timeline: March 28-April 5
March 28: The Italian fleet is decimated and nearly 2,500 sailors die when the British sink three of its cruisers and two destroyers at the Battle of Cape Matapan.
The Eagle Squadron, comprised of American pilots operating under the British flag, is ready for battle.
Plutonium-239, a uranium isotope that will prove critical in the development of nuclear weapons, is discovered by a team of American physicists.
March 29: The Royal Navy traps Italian warships in waters between Greece and Crete. Three Italian cruisers are sunk and an important Italian battleship, Vittorio Veneto, is badly damaged.
March 30: The U.S. Navy commandeers ships flying the flags of Axis nations stationed in ports across the United States.
April 2-3: Count Teleki, the prime minister of Hungary, takes his own life because Hungary is joining Germany in an invasion of Yugoslavia, with which he had signed a non-aggression treaty.
April 3: Stafford Cripps, the British ambassador to Moscow, delivers a warning to Joseph Stalin from Winston Churchill that an attack on the Soviet Union by Nazi Germany could happen any day.
April 4: Under pressure from the advancing Allies, the Italians abandon the Ethiopian capital of Addis Ababa. South African troops will occupy the city for the Allies on the 6th.
Adolf Hitler assures Japanese leaders that Germany will fight the United States if Japan attacks the U.S. in the Pacific.
April 5: The Soviet air force test-flies its new MiG-3 fighter for the first time.
The gulf between Adolf Hitler and Joseph Stalin grows when Yugoslavia signs a non-aggression treaty with the Soviet Union, drawing the ire of the Nazi Germans.
World War II Headlines
Below are more images and headlines about World War II events from April 1941.
British unwelcome in Iraq: Indian troops guard an Iraqi oil refinery in 1941. Iraq had been independent since 1932, but Britain retained privileges there. The British maintained air bases at Habbaniya and Basra, had the right to pass troops through Iraq, and held commercial interest in oil refineries. The wartime government was initially pro-British, but on April 3, 1941, pro-Axis Rashid Ali El-Ghailani became prime minister following a coup. Britain dispatched a brigade to Basra, but Rashid Ali refused entry to further brigades until it left. Iraqi troops surrounded Habbaniya, but British aircraft and the garrison defeated them by early May. British reinforcements arrived, and Rashid Ali fled to Germany.
On the following page is a World War II timeline summarizing more important World War II events from April 1941.