November 5, 1940 - President Franklin D. Roosevelt continues his dominance of presidential politics winning his third presidential election. Roosevelt becomes the first man to hold office for three terms.
December 7, 1941 -
The attack on Pearl Harbor, 1,177 sailor and marines perishing in the attack, as well as the loss or damage to twenty-one naval ships, led to the entry of American troops into World War II.
June 4-7, 1942 - The Battle of the Midway is fought at Midway Islands in the Pacific with the Japanese fleet encountering its first major defeat of the war against the United States military.
June 21, 1943 - Race riots in Detroit and Harlem cause forty deaths and seven hundred injuries.
June 6, 1944 - The Normandy Invasion, D-Day, occurs when one hundred and fifty-five thousand Allied troops, including American forces and those of eleven other Allied nations (Australia, Belgium, Canada, Czechoslovakia, France, Greece, the Netherlands, New Zealand, Norway, Poland, and the United Kingdom) land in France.
August 6, 1945 - President Harry S. Truman gives the go-ahead for the use of the atomic bomb with the bombing of Hiroshima. Three days later, the second bomb is dropped on Nagasaki, Japan. On August 15, Emperor Hirohito of Japan surrenders.
January 10, 1946 - The first meeting of the United Nations general assembly occurs
April 15, 1947 - Jackie Robinson breaks Major League Baseball's barrier against colored players when he debuts at first base for Branch Rickey's Brooklyn Dodgers.
April 1, 1948 - The Soviet Union begins its land blockade of the Allied sectors of Berlin, Germany
April 4, 1949 - NATO, the North American Treaty Organization, is formed by the United States, Canada, and ten Western European nations