Deaths on March 31

Clifford Shull, American physicist and academic, Nobel Prize laureate (b. 1915)

Clifford Glenwood Shull (September 23, 1915 in Pittsburgh, Pennsylvania – March 31, 2001) was a Nobel Prize-winning American physicist.

6 May

Pope John Paul II
During a trip to Syria, Pope John Paul II becomes the first pope to enter a mosque.
11 Sep

September 11 attacks
Two hijacked aircraft crash into the World Trade Center in New York City, while a third smashes into The Pentagon in Arlington County, Virginia, and a fourth into a field near Shanksville, Pennsylvania, in a series of coordinated suicide attacks by 19 members of al-Qaeda. A total of 2,996 people are killed.
14 Sep

September 11, 2001 attacks
Historic National Prayer Service held at Washington National Cathedral for victims of the September 11 attacks. A similar service is held in Canada on Parliament Hill, the largest vigil ever held in the nation's capital.
17 Sep

September 11 attacks
The New York Stock Exchange reopens for trading after the September 11 attacks, the longest closure since the Great Depression.
7 Oct

War in Afghanistan (2001-2014)
The Global War on Terrorism begins as a result of the September 11 attacks. The U.S. invasion of Afghanistan initiates with an air assault and covert operations on the ground.