1066 – William the Conqueror, the duke of Normandy, invades England on the southeast coast. He defeats King Harold II at the Battle of Hastings.
1918 – A Liberty Loan parade in Philadelphia exposes thousands to the Spanish flu, prompting a huge outbreak. The flu kills an estimated 20 million to 50 million people worldwide.
1928 – Sir Alexander Fleming, a young bacteriologist, accidentally discovers penicillin, one of the great developments in modern medicine.
1941 – Boston Red Sox’s Ted Williams plays a double-header on the last day of the regular season and gets six hits in eight trips to the plate, boosting his batting average to .406, the first player since Bill Terry in 1930 to hit .400.