September 27 is the 270th day of the year (271st in leap years) in the Gregorian calendar; 95 days remain until the end of the year.
1066 – William the Conqueror and his army set sail from the mouth of the Somme river, beginning the Norman conquest of England.
1590 – The death of Pope Urban VII, 13 days after being chosen as the Pope, ends the shortest papal reign in history.
1777 – American Revolution: Lancaster, Pennsylvania becomes the capital of the United States for one day after Congress evacuates Philadelphia.
1822 – Jean-François Champollion officially informs the Académie des Inscriptions et Belles Lettres in France that he has deciphered the Rosetta Stone.[7]
1825 – The world's first public railway to use steam locomotives, the Stockton and Darlington Railway, is ceremonially opened.[8]
1854 – The paddle steamer SS Arctic, owned by the Collins Line of New York, sinks off the coast of Newfoundland, following a collision with a smaller vessel, the SS Vesta. Only 88 of over 300 people on board survive. About a dozen of the occupants of the Vesta are killed when their lifeboat is hit by the Arctic.
1875 – The merchant sailing ship Ellen Southard is wrecked in a storm at Liverpool.
1903 – 'Wreck of the Old 97': an American rail disaster, in which 11 people are killed; it later becomes the subject of a popular ballad.[10]
1908 – Production of the Model T automobile begins at the Ford Piquette Avenue Plant in Detroit.
1928 – The Republic of China is recognized by the United States.
1938 – The ocean liner Queen Elizabeth is launched in Glasgow.
1940 – World War II: The Tripartite Pact is signed in Berlin by Germany, Japan and Italy.
1941 – The SS Patrick Henry is launched, becoming the first of more than 2,700 Liberty ships.
1942 – Last day of the Matanikau action on Guadalcanal as United States Marines barely escape after being surrounded by Japanese forces.
1944 – The Kassel Mission results in the largest loss by a USAAF group on any mission in World War II.
1962 – Rachel Carson's book Silent Spring is published, inspiring an environmental movement and the creation of the U.S. Environmental Protection Agency.
1996 – The Battle of Kabul ends in a Taliban victory; an Islamic Emirate of Afghanistan is established.