He continued to lead his regiment during the first phase of the Atlanta Campaign in 1864. During the Siege of Atlanta, he assumed command of the 2nd Brigade, 3rd Division, XXIII Corps. Casement's 2nd Brigade was at the center of the Union line at the Battle of Franklin on November 30, 1864. Confederate Lt. Gen. John Bell Hood's Army of Tennessee conducted numerous frontal assaults against fortified positions occupied by the Union forces under Maj. Gen. John M. Schofield. Hood's forces struck Casement's brigade with multiple waves of brigade assaults—probably as many as six distinct attacks. All of these assaults were turned back with heavy losses. The Confederate assault of six infantry divisions containing eighteen brigades with 100 regiments numbering almost 20,000 men, sometimes called the "Pickett's Charge of the West", resulted in devastating losses to the men and the leadership of the Army of Tennessee. Casement's commanding officer, Jacob D. Cox, credited him with "saving the day for the Union." Casement was appointed as a brigadier general by brevet commission in January 1865.