The Battle of Palmito Ranch, also known as the Battle of Palmito Hill, is considered by some criteria as the final battle of the American Civil War. It was fought May 12 and 13, 1865, on the banks of the Rio Grande east of Brownsville, Texas, and a few miles from the seaport of Los Brazos de Santiago, at the southern tip of Texas. The battle took place more than a month after the general surrender of Confederate forces to Union forces at Appomattox Court House, which had since been communicated to both commanders at Palmito, and in the intervening weeks the Confederacy had collapsed entirely, so it could also be classified as a postwar action.

Union and Confederate forces in southern Texas had been observing an unofficial truce since the beginning of 1865, but Union Colonel Theodore H. Barrett, newly assigned to command an all-black unit and never having been involved in combat, ordered an attack on a Confederate camp near Fort Brown for unknown reasons. The Union attackers captured a few prisoners, but the following day the attack was repulsed near Palmito Ranch by Colonel John Salmon Ford, and the battle resulted in a Confederate victory. Union forces were surprised by artillery said to have been supplied by the French Army garrison occupying the up-river Mexican town of Matamoros.

Casualty estimates are not dependable, but Union Private John J. Williams of the 34th Indiana Infantry Regiment is believed to have been the last man killed during the engagement. He could then arguably be reckoned as the last man killed in the war.