- Aug 1 Battle of Little Rock, Arkansas; start of Chattanooga campaign
- Aug 1 Cavalry action near Brandy Station-End of Gettysburg Campaign
- Aug 3 Governor Seymour asks President Lincoln to suspend draft in New York
- Aug 8 American Civil War: Tennessee's "military" Governor Andrew Johnson frees his personal slaves. Celebrated as a holiday by Tennessee African Americans (early 20th century)
- Aug 9 Skirmish at Calfkiller Creek, Tennessee - Union troops attack Confederate scouts
- Aug 11 Cambodia becomes French protectorate
- Aug 12 1st cargo of lumber leaves Burrard Inlet (Vancouver, BC)
- Aug 15 Confederate submarine "CSS H.L. Hunley" arrives in Charleston on railroad cars from Mobile, Alabama, where it was built [1]
- Aug 15 The Anglo-Satsuma War begins between the Satsuma Domain of Japan and the United Kingdom (Traditional Japanese date: July 2, 1863).
- Aug 16 Chickamauga campaign of the US Civil War begins in Georgia
- Aug 17 Federal batteries & ships attacked Fort Sumter in South Carolina
Lawrence Massacre
Aug 21 Lawrence Massacre [Quantrill's raid]: 450 Confederate guerrillas led by William Quantrill with William T. Anderson and Frank James attack the Unionist town of Lawrence, Kansas, killing more than 150 unarmed men and boys
- Aug 26 Battle of Rocky Gap, West Virginia (White Sulphur Springs): Colonel George S. Patton's Confederate forces defeat Union brigade advance
Admirals
Aviators
Gangsters
Generals
Industrialists
Suffragists