On May 10

Syrian civil war: The Syrian Democratic Forces, assisted by the U.S. military, captured the Tabqa Dam and surrounding countryside, completing the Battle of Tabqa.

One World Trade Center (pictured) in New York City, the tallest building in the Western Hemisphere, was topped out at a height of 1,776 feet (541 m).

Vladimir Arutyunian attempted to assassinate U.S. president George W. Bush and Georgian president Mikheil Saakashvili in Tbilisi using a hand grenade, which failed to detonate.

An earthquake registering 7.3 Mw struck near Qaen, Iran, killing at least 1,567 and leaving around 50,000 others homeless.

American serial killer John Wayne Gacy was executed by lethal injection for the murders of twelve teenage boys and young men in a series of killings committed between 1972 and 1978.

World War II: German Deputy Führer Rudolf Hess parachuted into Scotland in an attempt to negotiate peace with the British government.

British prime minister Neville Chamberlain resigned and formally recommended Winston Churchill as his successor.

World War II: German forces commenced their invasion of Belgium.

As part of Nazi Germany's persecution of transgender people, thousands of books taken from the Institute for Sexual Science were burned in Bebelplatz square for being "un-German".

Ernest Shackleton and five companions arrived at South Georgia, completing a 1,300 km (800 mi) lifeboat voyage (launch pictured) over 16 days to obtain rescue for the Imperial Trans-Antarctic Expedition.

Siamese–Vietnamese wars: Lê Văn Khôi escaped from prison to begin a revolt against Emperor Minh Mạng, primarily to avenge his adoptive father, Vietnamese general Lê Văn Duyệt.

American Revolutionary War: A small force of Patriots led by Ethan Allen and Benedict Arnold captured Fort Ticonderoga (depicted) in New York, without significant injury or incident.

Dutch explorer Pieter Nuyts was appointed governor of Formosa (modern-day Taiwan) by the Dutch East India Company.