Artillery atop Marye's Heights and nearby elevations would thoroughly blanket the Federal approach. Sumner's first assault began at noon and set the pattern for a ghastly series of attacks that continued, one after another, until dark. As soon as the Northerners marched out of Fredericksburg, Longstreet's artillery wreaked havoc on the crisp blue formations. The Unionists then encountered a deadly bottleneck at the canal ditch which was spanned by partially-destroyed bridges at only three places. Once across this obstacle, the attackers established shallow battle lines under cover of a slight bluff that shielded them from Reel eyes.
Orders then rang out for the final advance.
The landscape beyond the canal ditch contained a few buildings and fences, but from the military perspective it provided virtually no protection. Dozens of Southern cannon immediately reopened on the easy targets and when the Federals traversed about half the remaining distance, as sheet of flame spewed forth from the Sunken Road. This rifle fire decimated the Northerners. Survivors found refuge behind a small swale in the ground or retreated back to the canal ditch valley. Although General Cobb suffered a mortal wound early in the action, the Southern line remained firm.