2018-05-20

A tornado struck Moore, Oklahoma, United States, killing 24 people and causing an estimated $2 billion of damage.

The first of two major earthquakes struck Northern Italy, resulting in seven deaths.

In deciding Romer v. Evans, the U.S. Supreme Court struck down a constitutional amendment in Colorado that prevented protected status under the law for homosexuals or bisexuals.

While attempting to land at Cairo International Airport, Pakistan International Airlines Flight 705 crashed for unknown reasons, killing all but 6 of the 121 people on board.

The first session of the National Diet opened in Tokyo, Japan.

The Luttra Woman, a bog body from the Early Neolithic period, was discovered near Luttra, Sweden.

World War II: German paratroopers began the Battle of Heraklion on the island of Crete, capturing the airfield and port in Heraklion ten days later.

By the Treaty of Jeddah, the United Kingdom recognised the sovereignty of King Abdulaziz of Saudi Arabia (pictured) over Hejaz and Nejd, which later merged to become Saudi Arabia.

With the signing of the Treaty of Jeddah, the United Kingdom recognized the sovereignty of Ibn Saud over Hejaz and Nejd, which later merged to become Saudi Arabia.

Representatives from seventeen countries signed the Metre Convention, which set up an institute for the purpose of coordinating international metrology and for coordinating the development of the metric system.