August 6 is the 218th day of the year (219th in leap years) in the Gregorian calendar; 147 days remain until the end of the year.
1777 – American Revolutionary War: The bloody Battle of Oriskany prevents American relief of the Siege of Fort Stanwix.
1787 – Sixty proof sheets of the Constitution of the United States are delivered to the Constitutional Convention in Philadelphia, Pennsylvania.
1819 – Norwich University is founded in Vermont as the first private military school in the United States.
1862 – American Civil War: The Confederate ironclad CSS Arkansas is scuttled on the Mississippi River after engine failure near Baton Rouge, Louisiana.
1890 – At Auburn Prison in New York, murderer William Kemmler becomes the first person to be executed by electric chair.
1901 – Kiowa land in Oklahoma is opened for white settlement, effectively dissolving the contiguous reservation.
1926 – Gertrude Ederle becomes the first woman to swim across the English Channel.
1942 – Queen Wilhelmina of the Netherlands becomes the first reigning queen to address a joint session of the United States Congress.
1945 – World War II: Hiroshima, Japan is devastated when the atomic bomb 'Little Boy' is dropped by the United States B-29 Enola Gay. Around 70,000 people are killed instantly, and some tens of thousands die in subsequent years from burns and radiation poisoning.