An 1838 graduate of the U.S. Military Academy at West Point, N.Y., Hardee wrote the popular Rifle and Light Infantry Tactics in 1855. In 1856–60 he served as commandant of cadets at West Point.

When Georgia seceded from the Union in January 1861, Hardee resigned his commission and assumed command of Confederate forces in northeastern Arkansas. Promoted first to major general and then to lieutenant general, he amply demonstrated his military skills at the battles of Shiloh (April 1862), Perryville (October), Murfreesboro (December 1862–January 1863), and Chattanooga (November). He was one of the most brilliant corps commanders in the Army of the Tennessee. After taking part in the battles before Atlanta (May–September 1864), he assumed command of the military department of South Carolina, Georgia, and Florida, where he fought a dogged if unsuccessful rearguard action attempting to stem the advance of General William T. Sherman across Georgia. He joined forces with General Joseph E. Johnston shortly before the Confederate surrender (April 1865). After the war he retired to his plantation near Selma, Ala.