- Aug 5 Thomas Williams, US Union brigadier general, dies in battle at 47
- Aug 6 Francisco Acuña de Figueroa, Uruguayan poet (Toraidas), dies at 71
- Aug 9 Charles S. Winder, American military officer and Confederate Brigadier General (US Army, 1850-61; Confederate Army, 1861-62), killed in the Battle of Cedar Mountain Virginia at 32
- Aug 9 Joseph Bennett Plummer, American Brigadier General (Union Army), dies at 42 or 46
- Aug 10 Hon'inbō Shūsaku, Japanese professional Go player, dies at 33
- Aug 22 Henry Bohlen, German/US brigadier general (Union), dies in battle at 51
- Aug 30 Charles Bernard Desormes, French physicist and chemist who determined the ratio of the specific heats of gases and the composition of carbon monoxide and carbon disulfide, dies at 91
- Aug 31 George William Taylor, US Union brigadier general, dies from injuries suffered in Battle of Manassas Station at 53
- Aug 31 Ignaz Assmayer, Austrian organist and liturgical composer, dies at 72
Assassination
Drug Overdose
Gunshot Wound
Murder
Plane Crash
Suicide