THURSDAY, Sept. 17, 2026

642-Arab forces under Amr ibn al-'As conquer Alexandria

1683-Dutch scientist Antonie van Leeuwenhoek is the first to report the existence of bacteria

1787-U.S. Constitution is signed by delegates at the Philadelphia Convention

1862-Battle of Antietam [Battle of Sharpsburg]: Bloodiest day in the American Civil War with 22,000 dead, wounded, or missing in the first major battle on Union soil

1916-World War I flying ace, the Red Baron of the German Luftstreitkräfte, wins his first aerial combat near Cambrai, France

1940-Adolf Hitler indefinitely postpones Operation Sealion, the planned German invasion of Great Britain

1978-Anwar Sadat, Menachem Begin, and Jimmy Carter sign the Camp David Accords, frameworks for peace in the Middle East and between Egypt and Israel