McLaws resigned from the United States Army in March 1861 to join the Confederate Army. He became a colonel in the 10th Georgia Infantry, soon to be promoted to brigadier general in September 1861. During the Peninsula campaign, he served as a division commander of the 1st corps of the Army of Northern Virginia, and earned himself a promotion to major general in May 1862. In December 1863, during the Knoxville campaign, he had to replaced by Gen. James Longstreet. He was soon restored to command, however, the controversy led to his relocation to a command in Georgia. He served in command of the Union forces at the battle of Rivers' Bridge, South Carolina in February 1865. He served under Gen. Joseph E. Johnston until his surrender at Greensboro, North Carolina.