By the following month, Anderson had enlisted in the Confederate Army, having joined the "Liberty Hall Volunteers," a group of Washington College students and alumni, who became part of the Fourth Virginia Infantry Regiment under the command of former Virginia Military Institute professor Stonewall Jackson. A bullet shattered Anderson's kneecap at the Battle of First Manassas on July 21, and he was mustered out for disability by September 13, 1861. However, he joined a temporary artillery company in