regimental commanders in Whiting's two brigades were killed or wounded, as well as Captain William Balthis, the division's chief of artillery. Pickett's brigade also succeeded in its second assault of the day. Confederate breakthroughs on their center and right could not be countered, and the Union line crumbled. A total of nine Union regimental commanders were killed or mortally wounded in the battle. Most of the 4th New Jersey, along with its colonel, were surrounded and taken prisoner by Longstreet's division; a lieutenant colonel assumed command of the remaining men in the regiment. Sykes's regulars conducted an orderly withdrawal from the McGehee house to Grapevine Bridge. The Union brigades of Brig. Gens. Thomas F. Meagher and William H. French arrived from the II Corps too late to help, other than as a rear guard for Porter's retreat. A battalion of the 5th U.S. Cavalry under Captain Charles J. Whiting made a desperate charge against the Texas Brigade, but were forced to surrender after heavy losses. By 4 a.m. on June 28, Porter had withdrawn across the Chickahominy, burning the bridges behind him. During the retreat from Gaines' Mill, Brig. Gen John F. Reynolds was also captured by the Confederates while sleeping under a tree. Aftermath Gaines' Mill was an intense battle, the largest of the Seven Days and the only clear-cut Confederate tactical victory of the Peninsula Campaign. Union casualties from the 34,214 engaged were 6,837 (894 killed, 3,107 wounded, and 2,836 captured or missing). Of the 57,018 Confederates engaged, losses totaled 7,993 (1,483 killed, 6,402 wounded, 108 missing or captured) including the loss of three brigade commanders and one general officer. For comparison, no Union general officers were killed or wounded and only one brigade commander, Col. Warren, who remained on the field (the chief of McCall's artillery, Maj. Henry DeHart, was also mortally wounded). Since the Confederate assault was conducted against only a small portion of the Union Army (the V Corps, one fifth of the army), the army emerged from the battle in relatively good shape overall. Lee's victory, his first of the war, could have been more complete if it were not for the mishaps of Stonewall Jackson. Historian Stephen W. Sears speculates that were it not for Jackson's misdirected march and his poor staff work, the major assault that Lee unleashed at 7 p.m. could have occurred three or four hours earlier. This would have