Burnside led an amphibious attack against the Confederate defences on Roanoke Island at the mouths of both the Albemarle and Pamlico Sounds on the North Carolina coast. It was seen as key to attacking Richmond from behind. He directed a makeshift fleet of steamers mounting 64 guns against the under-manned and out gunned defensive batteries while his transports landed his overwhelming force of 13,000 troops on the undefended southern half of the island. A makeshift 'mosquito' fleet of Confederate vessels attempted to intercede, but made little impression, and the Union infantry managed to force a way through supposedly impenetrable swamp and quicksand to take the defenders in the flanks. Most surrendered, amd the island fell.