In History, Today on October 21

The People's Crusade, part of the First Crusade, is decisively defeated by the Seljuk forces at the Battle of Civetot.

Ferdinand Magellan discovers a strait now known as the Strait of Magellan, the passage immediately south of mainland South America connecting the Pacific and Atlantic Oceans.

The Battle of Trafalgar takes place, a naval engagement fought by the British Royal Navy against the combined fleets of France and Spain during the Napoleonic Wars, resulting in a decisive British victory.

Florence Nightingale and a staff of 38 nurses are sent to the Crimean War.

Thomas Edison invents a workable electric light at his laboratory in Menlo Park, New Jersey.

World War II: The first kamikaze attack occurs as a Japanese plane carrying a 200-kilogram bomb attacks HMAS Australia off Leyte Island.

The Solomon R. Guggenheim Museum, designed by Frank Lloyd Wright, opened to the public in New York City.

The Aberfan disaster occurs as a colliery spoil tip collapses in the Welsh village of Aberfan, killing 144 people, including 116 children.

A large Vietnam War protest occurs in Washington, D.C., as thousands of demonstrators march against the war.

The meter is defined as the distance light travels in a vacuum in 1/299,792,458 of a second, by the 17th General Conference on Weights and Measures.

The United States and its allies began a major military offensive in Afghanistan, targeting Taliban and al-Qaeda forces as part of Operation Enduring Freedom.

The final flight of the supersonic passenger airliner Concorde takes place from New York City to London Heathrow Airport, marking the end of an era in aviation history.

The Libyan National Transitional Council declares the liberation of Libya, marking the end of the Libyan Civil War following the death of Muammar Gaddafi.

Back to the Future Day was celebrated worldwide, marking the date that Marty McFly and Doc Brown traveled to in the movie 'Back to the Future Part II'.

Protests erupt in Chile over economic inequality and the cost of living, leading to widespread demonstrations and a state of emergency being declared.