It is the 102nd day of the year, with only 263 days remaining until the end of the year.
1204 - The Crusaders of the Fourth Crusade breach the walls of Constantinople and enter the city, which they completely occupy the following day.
1606 - The Union Jack, the flag, is adopted as that of Great Britain.
1633 - The formal inquest of Galileo Galilei by the Inquisition begins.
1861 - The American Civil War begins with Confederate forces firing on Fort Sumter, in the harbor of Charleston, South Carolina.
1864 - The Andrews Raid, known as the Great Locomotive Chase occurred, starting from Big Shanty, Georgia.
1864 - Confederate forces kill most of the African-American soldiers that surrender at Fort Pillow, Tennessee.
1935 - It is the first flight of the Bristol Blenheim, British aircraft.
1937 - Sir Frank Whittle ground-tests the first jet engine designed to power an aircraft, in Rugby, England.
1945 - President Franklin Roosevelt dies while in office, the vice-president Harry Truman is sworn in.
1954 - Baill Haley & His Comets record, "Rock Around the Clock" in New York City.
1955 - The polio vaccine, developed by Dr. Jonas Salk, is declared safe and effective.
1961 - The Russian cosmonaut Yrui Gagarin becomes the first human to travel into outer space and perform the first manned orbital flight, in Vostok 3KA-2.
1981 - The first launch of a space shuttle takes place on STS-1 mission.
1990 - Jim Gary's Twentieth Century Dinosaurs exhibition opens at the Smithsonian Museum of Natural History in Washington, D.C.
1999 - President Bill Clinton is cited for contempt of court for giving "intentionally false statements" in a sexual harassment civil lawsuit.