After capturing the outer line of defenses at Drewry's Bluff, Major General Benjamin F. Butler prepared to attack the main Confederate line, but after judging the earthworks too strong and his reserves too few, he canceled the attack and put the Army of the James on the defensive. Confederate commander General P.G.T. Beauregard then planned an attack, massing Major General Robert Ransom's division on the left to crush the Federal right and drive it west, assigning Major General Robert F. Hoke's division to support the attack against the Federal center and left, holding Brigadier General Alfred H. Colquitt's division in reserve, and directing Major General Chase Whiting's division at Swift Creek to move north along the Richmond Turnpike and block the Federal retreat southward. At 4:30 am on May 16, in heavy fog, Ransom's division attacked, pushing aside the pickets of the 2nd U.S. Colored Cavalry and smashing the brigade of General Charles Heckman, who was captured during the rout, but after Heckman's brigade collapsed, the rest of the Federal right held. When Ransom's attack stalled, Hoke attacked the Federal center with the brigades of Brigadier General Johnson Hagood and Brigadier General Bushrod Johnson; despite initial success, including Hagood's capture of some artillery, the Federal center held and repulsed the Confederate flanks. Colquitt then committed his former brigade from the reserve to strengthen the attack on the Federal right and center, while units of the 10th Corps shifted from the Federal left to the center and stabilized the line. Hoke also attacked the Federal left with the rest of his division and was repulsed, but General William F. Smith believed his 18th Corps was more damaged than it actually was and ordered a withdrawal, forcing the 10th Corps to withdraw as well. The Confederates were too disorganized and damaged to pursue, and near Walthall Junction Whiting failed to cut off the Federal retreat, allowing Butler's troops to return to their defensive positions in Bermuda Hundred. The Second Battle of Drewry's Bluff was the largest battle of the Bermuda Hundred Campaign, with over 30,000 troops engaged; the Army of the James suffered about 3,000 casualties in fighting from May 12-16, while Confederate forces suffered about 1,000.