The final battle of the Seven Days, July 1, consisted of uncoordinated Confederate assaults against the Union defenses—buttressed by artillery placements and the naval guns of the Union James River squadron—on Malvern Hill. McClellan was absent from the battlefield, instead remaining on the gunboat "Galena"; the Union corps commanders cooperated in selecting the positions for their troops but none of them exercised overall field command. Lee's army suffered over 5,600 casualties in this effort, compared to only 3,000 Union casualties. Although the Union corps commanders felt that they could hold the field against further Confederate attacks, McClellan ordered the army to retreat back to Harrison's Landing.