Kasparov-versus-computer chess match
On this day in 1996, world chess champion Garry Kasparov began a six-round match against Deep Blue, a chess-playing computer built by IBM, in which Kasparov claimed a 4–2 victory (though Deep Blue won a rematch the following year).

1975 British politician Margaret Thatcher was elected leader of the Conservative Party, replacing Edward Heath.

Chile's independence from Spain declared
Although the decisive victory over the Spanish did not come until April at the Battle of Maipú, Chile formally declared independence from Spain on this day in 1818, the first anniversary of Chile's victory at Chacabuco.

William and Mary crowned
Following the Glorious Revolution, William and Mary were proclaimed king and queen of England this day in 1689, after which they ruled jointly as King William III and Queen Mary II until her death in 1694.

Fatwa issued against Salman Rushdie
On this day in 1989, Ayatollah Ruhollah Khomeini of Iran issued a fatwa and offered a bounty for the assassination of author Salman Rushdie, whose novel The Satanic Verses (1988) Khomeini denounced as blasphemous.

1989 Under President Mikhail Gorbachev, the Soviet Union withdrew its last troops from Afghanistan after occupying the country since 1979.

Power in Cuba seized by Fidel Castro
After defeating the forces of dictator General Fulgencio Batista, Fidel Castro became premier of Cuba this day in 1959 and transformed the island country into the Western Hemisphere's first communist state.

Vietnam invaded by China
After the Vietnam War, Vietnam bolstered its ties with the Soviet Union rather than with China, and, following a series of anti-Chinese, pro-Soviet maneuvers by Vietnam, China invaded its southern neighbour this day in 1979.

Pluto discovered by Clyde Tombaugh
Using a 13-inch (33-cm) telescope at the Lowell Observatory in Flagstaff, Arizona, Clyde W. Tombaugh, a 24-year-old American with no formal training in astronomy, discovered the dwarf planet Pluto this day in 1930.

Iwo Jima invaded by U.S. Marines
On this day in 1945, during the final phases of World War II, U.S. Marines invaded Iwo Jima so as to wrest control of the strategically important island from the Japanese, who put up fierce resistance in the ensuing battle.

John Glenn's orbit of Earth
John H. Glenn, Jr., the oldest of seven astronauts selected by NASA for Project Mercury spaceflight training (and later a U.S. senator), became on this day in 1962 the first American to orbit Earth, doing so three times.

Malcolm X assassinated
Malcolm X, who articulated concepts of racial pride and black nationalism in the United States, was assassinated this day in 1965 and became an ideological hero after the posthumous release of The Autobiography of Malcolm X.

2011 After enduring more than five months of tremors, Christchurch, New Zealand, and its surrounding area were struck by a massive destructive aftershock (magnitude 6.3).

Alamo besieged by Santa Anna's Mexican army
This day in 1836, during the Texas war for independence, Mexican General Antonio López de Santa Anna began a siege of the Alamo, which was captured after 13 days and which became for Texans a symbol of heroic resistance.

U.S. President Andrew Johnson impeached
On this day in 1868, the U.S. House of Representatives voted 126–47 to impeach President Andrew Johnson, whose lenient Reconstruction policies regarding the South after the Civil War angered Radical Republicans in Congress.