Pike, not realizing that he was boxing himself into a potential trap. Sheridan found himself only two and half miles from his objective, but saw that the intermediate defenses in his front swarmed with enemy troops. His left flank was against the swollen Chickahominy, and Confederate cavalry threatened his rear, hoping to capture the Union force. Sheridan decided to force a crossing of the river at Meadow Bridge, where the Virginia Central Railroad crossed the river. He assigned the Michigan brigade of Brig. Gen. George A. Custer, part of Brig. Gen. Wesley Merritt's division, to seize the span and the high bluffs beyond. The rest of Sheridan's command had to hold the Confederates at bay while Custer executed his orders. The rearguard of Brig. Gen. David McM. Gregg's division was assailed on three sides when it was light enough for a brigade of Confederate infantry to sally forth from the fortifications and attack. Soon, other Confederates, including Richmond citizens hastily pressed into military service, joined in the efforts to break through the rear lines. James H. Wilson's men were initially pushed back in some confusion, but Gregg had concealed a heavy line of skirmishers armed with repeating carbines in a brushy ravine. His men poured forth a destructive fire, halting the final Confederate advances, assisted by some of Wilson's men who turned the flank of the attacking column. Federal horse artillery made sure that the Confederate infantry no longer was a threat, and three mounted cavalry regiments skirmished with approaching enemy cavalry, turning them aside and protecting the rear. In the meantime, Custer's 5th Michigan Cavalry used snipers to suppress Confederate rifle fire while several daring dismounted troopers crossed the damaged railroad bridge, hopping from railroad tie to tie while menaced by persistent enemy artillery fire. Followed by the 6th Michigan, they succeeded in the early afternoon in clearing the north bank of the Chickahominy and gaining a foothold on the Confederate side of the river. Custer's men pinned down remaining threatening enemy units and captured two artillery pieces, while pioneers energetically planked the bridge to provide safe passage for large numbers of men and horses. By mid-afternoon, Merritt's entire division had crossed and engaged the Confederate hasty works on Richmond Heights, driving the defenders back to Gaines's Mill. By 4 p.m., the rest of Sheridan's cavalry had crossed the river. Sheridan destroyed the Virginia Central Bridge in his wake