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 the 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 hastily built Confederate 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.