On September 14

Drone attacks on major processing facilities at Abqaiq and Khurais forced Saudi Arabia to cut more than half of its oil production.

Physicists of the LIGO and Virgo projects first observed gravitational waves, the existence of which was predicted by Henri Poincaré in 1905.

Late-2000s financial crisis: The Northern Rock bank received a liquidity support facility from the Bank of England, sparking a bank run—the United Kingdom's first in 150 years.

President Kumba Ialá (pictured) of Guinea-Bissau was deposed in a bloodless military coup.

The Constitutional Court of Bosnia and Herzegovina declared the breakaway Croatian Republic of Herzeg-Bosnia to be unconstitutional.

Typhoon Sarah dissipated after causing extensive damage along an erratic path across the Western Pacific, killing 71 in Taiwan, the Philippines, and the Gotō Islands.

Afghan president Nur Muhammad Taraki (pictured) was overthrown and later killed on the orders of Hafizullah Amin, who succeeded him.

At a conference held in Baghdad, the governments of Iran, Iraq, Kuwait, Saudi Arabia, and Venezuela founded OPEC to help coordinate their petroleum policies and influence global oil prices.

World War II: Nazi forces began a mass extermination campaign against the civilian residents of around 20 villages on the Greek island of Crete, eventually killing more than 500 men.

Hungarian forces massacred at least 150 ethnic Romanians in Ip, Transylvania, following rumors that Romanians were responsible for the deaths of two soldiers.

HMAS AE1 (pictured), the Royal Australian Navy's first submarine, was lost at sea; its wreck was not found until 2017.

Theodore Roosevelt became President of the United States at age 42, the youngest person ever to do so, eight days after William McKinley was fatally wounded in Buffalo, New York.

American Civil War: The Little Rock campaign ended with the Union Army capturing Little Rock, Arkansas.

Under the terms of the Calendar (New Style) Act 1750, the British Empire adopted the Gregorian calendar, skipping 11 days of the month.

António Manoel de Vilhena, Grand Master of the Knights Hospitaller, laid the first stone of Fort Manoel in Malta.

Viking activity in the British Isles: A coalition of native Irish, led by Niall Glúndub, failed in their attempt to drive the Vikings of the Uí Ímair from Ireland.

Domitian, the last Flavian emperor of Rome, was confirmed by the Senate to succeed his brother Titus.