General William Tecumseh Sherman lost a whole regiment on August 11th 1864 during the siege of Atlanta Georgia. The loss however was not due to fighting. The 1st Regiment of East Tennessee Infantry had been the first opponents of secession to volunteer for the Union Army in August 1861. and their three year were up.
The commander of the Army of the Ohio, General John McAllister Schofield issued a special order honoring the First for its service to the Union cause. The soldiers were told take a train to Knoxville Tennessee, where they were mustered out of the service.