Today in History: April 20

1999: Two students enter Columbine High School in Littleton, Colorado and open fire with multiple firearms, killing 13 students and teachers, wounding 25 and eventually shooting themselves.

1968: Pierre Elliott Trudeau of the Liberal Party, who became prime minister of Canada this day in 1968, discouraged the French separatist movement, oversaw the formation of a new constitution, and established relations with China.

1967: U.S. planes bomb Haiphong for first time during the Vietnam War.

1962: The New Orleans Citizens Committee gives free one-way ride to blacks to move North.

1953: Operation Little Switch begins in Korea, the exchange of sick and wounded prisoners of war.

1951: General MacArthur addresses a joint session of Congress after being relieved by President Truman.

1945: Soviet troops begin their attack on Berlin.

1942: Pierre Laval, the premier of Vichy France, in a radio broadcast, establishes a policy of "true reconciliation with Germany."

1940: The first electron microscope is demonstrated.

1924: Finalizing the dissolution of the Ottoman Empire, Turkey's Grand National Assembly voted to adopt a full republican constitution, with General Mustafa Kemal, who had first proclaimed the Turkish republic about six months earlier, becoming the first president of the republic.

1920: U.S. Supreme Court Justice John Paul Stevens was born in Chicago.

1919: In an ongoing dispute over the possession of Vilnius, Polish forces drove out Russia's Red Army—which had previously ousted the newly established Lithuanian government—and occupied the city.

1916: Wrigley Field opens in Chicago.

1879: The first mobile home (horse-drawn) is used in a journey from London to Cyprus.

1871: Japan's first government-operated postal service opened between Tokyo and Ōsaka.

1861: Robert E. Lee resigns from the U.S. Army.

1841: Edgar Allen Poe's first detective story is published.

1840: French Symbolist painter Odilon Redon was born in Bordeaux.

1836: The Territory of Wisconsin is created.

1809: Napoleon defeats Austria at Battle of Abensberg, Bavaria.

1792: France declares war on Austria, Prussia, and Sardinia.

1775: British troops begin the siege of Boston.

1770: Captain Cook discovers Australia.

1769: Ottawa Chief Pontiac is murdered by an Indian in Cahokia.

1657: English Admiral Robert Blake fights his last battle when he destroys the Spanish fleet in Santa Cruz Bay.

1653: England's Rump Parliament was dissolved by Oliver Cromwell and later replaced by the nominated Barebones Parliament, which was dissolved in the same year, leading to the declaration of the Protectorate.

1139: The Second Lateran Council opens in Rome.

1808: Napoleon III, president of the Second Republic (1850–52) and emperor of France (1852–70), was born in Paris.