August 24 – Confederate raider C.S.S. Alabama, captained by Raphael Semmes, is commissioned for service.
August 25 – Lincoln agrees to allow blacks to serve in the Union army, authorizing South Carolina military governor, General Rufus Saxton, to form five black regiments from the Sea Islands area. The regiments will be led by white officers.
August 28-30 — Confederates win the battle of Second Manassas (Bull Run II) led by Robert E. Lee. After the battle, Secretary of War Edwin Stanton calls for assistance from volunteer nurses. Males and females respond Clara Barton performs sterlingly.