At the innermost abatis on Stony Point, a British eight-inch howitzer aimed toward the shallow waters of Haverstraw Bay guarded the southern flank, but the main American assault column captured it before it could be loaded or fired. Lieutenant John Roberts of the Royal Artillery reached the battery just as it fell and believed the Americans entered the upper work at the barrier at the same time he did. These attackers were the vanguard of the American south column, which had waded through the bay and around the outward abatis. Their advance might have been stopped by a small British gunboat assigned to protect the area, but it was absent from its post. The rest of the column swept around the summit and approached the Upper Works from the rear, while at about the same time on the other side of Stony Point, the north column of Light Infantry entered the inner abatis and met fierce resistance from the defenders.