1533 - Henry VIII divorced his first wife, Catherine of Aragon.
1814 - The allied European nations against Napoleon marched into Paris.
1822 - Florida became a U.S. territory.
1842 - Dr. Crawford W. Long performed the first operation while his patient was anesthetized by ether.
1855 - About 5,000 "Border Ruffians" from western Missouri invaded the territory of Kansas and forced the election of a pro-slavery legislature. It was the first election in Kansas.
1856 - A peace treaty was signed between England and Russia. (Treaty of Paris)
1858 - Hyman L. Lipman of Philadelphia patented the pencil.
1867 - The U.S. purchased Alaska from Russia for $7.2 million dollars.
1870 - The 15th amendment, guaranteeing the right to vote regardless of race, was passed by the U.S. Congress.
1870 - Texas was readmitted to the Union.
1903 - Revolutionary activity in the Dominican Republic brought U.S. troops to Santo Domingo to protect American interests.
1905 - U.S. President Theodore Roosevelt was chosen to mediate in the Russo-Japanese peace talks.
1909 - The Queensboro bridge in New York opened linking Manhattan and Queens. It was the first double decker bridge.
1909 - In Oklahoma, Seminole Indians revolted against meager pay for government jobs.
1916 - Pancho Villa killed 172 at the Guerrero garrison in Mexico.
1936 - Britain announced a naval construction program of 38 warships.
1939 - The comic book "Detective Comics #27" appeared on newstands. This comic introduced Batman.
1940 - The Japanese set up a puppet government called Manchuko in Nanking, China.
1941 - The German Afrika Korps under General Erwin Rommel began its first offensive against British forces in Libya.
1944 - The U.S. fleet attacked Palau, near the Philippines.
1945 - The U.S.S.R. invaded Austria during World War II.
1946 - The Allies seized 1,000 Nazis attempting to revive the Nazi party in Frankfurt.
1947 - Lord Mountbatten arrived in India as the new Viceroy.
1950 - The invention of the phototransistor was announced.
1950 - U.S. President Truman denounced Senator Joe McCarthy as a saboteur of U.S. foreign policy.
1957 - Tunisia and Morocco signed a friendship treaty in Rabat.
1958 - The Alvin Ailey American Dance Theater gave its initial performance.
1964 - "Jeopardy" debuted on NBC-TV.
1964 - John Glenn withdrew from the Ohio race for U.S. Senate because of injuries suffered in a fall.
1970 - "Applause" opened on Broadway.
1970 - "Another World - Somerset" debuted on NBC-TV.
1972 - The British government assumed direct rule over Northern Ireland.
1972 - The Eastertide Offensive began when North Vietnamese troops crossed into the Demilitarized Zone (DMZ) in the northern portion of South Vietnam.
1975 - As the North Vietnamese forces moved toward Saigon South Vietnamese soldiers mob rescue jets in desperation.
1981 - U.S. President Ronald Reagan was shot and wounded in Washington, DC, by John W. Hinckley Jr. Two police officers and Press Secretary James Brady were also wounded.
1982 - The space shuttle Columbia completed its third and its longest test flight after 8 days in space.
1984 - The U.S. ended its participation in the multinational peace force in Lebanon.
1987 - Vincent Van Gogh's "Sunflowers" was bought for $39.85 million.
1993 - In Sarajevo, two Serb militiamen were sentenced to death for war crimes committed in Bosnia.
1993 - In the Peanuts comic strip, Charlie Brown hit his first home run.
1994 - Serbs and Croats signed a cease-fire to end their war in Croatia while Bosnian Muslims and Serbs continued to fight each other.
1998 - Rolls-Royce was purchased by BMW in a $570 million deal.
2002 - An unmanned U.S. spy plan crashed at sea in the Southern Philippines.
2002 - Suspected Islamic militants set off several grenades at a temple in Indian-controlled Kashmir. Four civilians, four policemen and two attackers were killed and 20 people were injured.
2009 - The Port Authority of New York and New Jersey confirmed that the new World Trade Center building would be officially known by its legal name of "One World Trade Center."