The 7th Michigan, commanded by Lt. Col. Henry Baxter, and 19th Massachusetts Infantry led the river assault in successive waves. The plan called for the bridge to be completed as the assault proceeded and for the 20th Massachusetts and three other regiments of the brigade to cross on the finished bridge. As the Fredericksburg-side bluff blocked rifle fire past the centerline of the river, the Confederate sharpshooters in Fredericksburg continued to fire on the bridge-builders. The uncompleted bridge forced the 20th Massachusetts to return and cross by pontoon-boats. The three regiments established a foothold and put sufficient pressure to force Confederate withdrawal (after 15 hours), and the first American combat river assault was concluded successfully.