What Happened Today in History on September 20

Arab forces led by Caliph Umar conquer the city of Alexandria, Egypt, ending Byzantine control and marking a significant moment in the Arab conquests.

During the Norwegian Crusade, the Crusaders, led by Sigurd I of Norway, arrive in Lisbon, Portugal, and establish a temporary alliance with King Afonso I against the Moors.

Clement VII is elected on September 20, 1378 as a rival pope in Avignon by a majority of the cardinals seceding from Rome. The events leading to the Western Schism began after Pope Gregory XI's death in March 1378, with the election of Urban VI on April 8, 1378, Expand +

Portuguese navigator Ferdinand Magellan, sets sail from Sanlucar de Barrameda in southern Spain with five ships and a crew of 270 men, on what become the first circumnavigation of the world and the first European explorer to reach the Pacific Ocean from the Atlantic.  Expand +

The signing of the Treaties of Ryswick begins, bringing an end to the Nine Years' War between France and the Grand Alliance of European powers. The last treaty was signed on October 30th 1697. More

September 20 - After more than two years exploring the western wilderness, the returning Lewis and Clark's Corps of Discovery arrives at the frontier village of La Charette, in modern Missouri. More

Forces of the Royal Italian Army enter Rome and take control of the city; eliminating the last remnants of the Papal territories and marking the end of the temporal power of the Pope.  Expand +

Hurricane Maria devastates Puerto Rico, causing nearly 3,000 deaths and major damage estimated to be $90 billion according to official estimates.

Millions participate in a Global Climate Strike, led by Greta Thunberg.