What happened on April 4 ?

1581 - Francis Drake completes a circumnavigation of the world and is knighted by Elizabeth I.

1660 - Declaration of Breda by King Charles II of England.

1721 - Sir Robert Walpole enters office as the first Prime Minister of the United Kingdom under King George I.

1812 - U.S. President James Madison enacted a ninety-day embargo on trade with the United Kingdom.

1814 - Napoleon abdicates for the first time.

1818 - The United States Congress adopts the flag of the United States as having 13 red and white stripes and one star for each state (20 stars) with additional stars to be added whenever a new state is added to the Union.

1841 - President William Henry Harrison dies of pneumonia becoming the first President of the United States to die in office and at one month, the elected president with the shortest term served.

1850 - Los Angeles, California is incorporated as a city.

1859 - Bryant's Minstrels debut "Dixie" in New York City in the finale of a blackface minstrel show.

1865 - American Civil War: A day after Union forces capture Richmond, Virginia, U.S. President Abraham Lincoln visits the Confederate capital.

1866 - Alexander II of Russia narrowly escapes an assassination attempt in the city of Kiev. A design for a city gate to commemorate his escape was the inspiration for Mussorgsky's The Great Gate of Kiev from Pictures at an Exhibition.

1887 - Argonia, Kansas elects Susanna M. Salter as the first female mayor in the United States.

1905 - In India, an earthquake near Kangra kills 370,000.

1918 - World War I: Second Battle of the Somme ends.

1939 - Faisal II becomes King of Iraq.

1945 - World War II: American troops liberate Ohrdruf death camp in Germany.

1945 - World War II: Soviet Army liberates Hungary.

1949 - Twelve nations sign The North Atlantic Treaty creating the North Atlantic Treaty Organisation.

1964 - The Beatles occupy all of the top five positions on the Billboard singles chart in the United States.

1968 - Martin Luther King Jr. assassinated in Memphis, Tennessee.

1968 - Apollo program: NASA launches Apollo 6.

1969 - Dr. Denton Cooley implants the first temporary artificial heart.

1973 - The World Trade Center in New York is officially dedicated.

1975 - Microsoft is founded as a partnership between Bill Gates and Paul Allen in Albuquerque, New Mexico

1975 - Vietnam War: Operation Baby Lift - A United States Air Force C-5A Galaxy crashes near Saigon, South Vietnam shortly after takeoff, transporting orphans. 172 people are killed.

1976 - Prince Norodom Sihanouk resigns as leader of Cambodia and is placed under house arrest.

1979 - President Zulfikar Ali Bhutto of Pakistan is executed.

1983 - Space Shuttle Challenger makes its maiden voyage into space.

1984 - President Ronald Reagan calls for an international ban on chemical weapons.

1988 - Governor Evan Mecham of Arizona is convicted in his impeachment trial and removed from office.

1991 - Senator John Heinz of Pennsylvania and six others are killed when a helicopter collides with their plane over Merion, Pennsylvania.

1994 - Netscape Communications Corporation is founded (under the name "Mosaic Communications Corporation") by Marc Andreessen and Jim Clark.