Fort Wagner guarded the southern approach to the key Confederate port of Charleston. Bridging Morris Island, its flanks were protected by the swampy Vincent’s Creek to landward, and the Atlantic Ocean. A water-filled trench, palisades of sharpened palmetto stakes and landmines further protected its approaches. One Union assault had already been repulsed on 11 July, with heavy losses. On the 18th, after launching a diversionary assault on James Island, Union General Quincy Gilmore once more tackled Wagner. The attack began with an eight-hour cannonade from six Union ironclads, and newly designed shore-breaching batteries. But Wagner’s thick earth and sand walls simply absorbed the bombardment. A coloured regiment, the 54th Massachusetts, spearheaded the evening assault. After two hours of heavy losses, the attack was abandoned. The Fort would be evacuated on 7 September, after two months of constant bombardment, the pervading stench of death impossible to bear.