A “desperate” assault upon Wagner the following morning failed, though the parapet was briefly gained. General Gillmore established counterbatteries and tried again on the 18th. From noon until nightfall that day “without cessation or intermission,” Federal guns poured a “storm of shot and shell upon Fort Wagner ... perhaps unequalled in history”; then, some 6,000 troops assaulted—in the van, the 54th Massachusetts, “the first colored regiment of the North to go to war.” In a short savage struggle, Seymour’s force suffered 1,500 casualties. Though one angle of the fort was gained and held for a time, the attack was repulsed. Thwarted in his plan to secure easy possession of Morris Island as a base for breaching operations against Fort Sumter, General Gillmore now determined to attempt that fort’s reduction from the ground already in his possession. Batteries Wagner and Gregg would be taken by protracted siege operations. At Fort Sumter, removal of guns and ammunition continued apace. Anticipating that Sumter was “liable to be silenced sooner or later,” and fearing attack at other points about the harbor, the Confederate authorities husbanded their resources. By mid-August, Fort Sumter’s armament was reduced to a safe minimum of 38 guns and 2 mortars. At distances of 2 to 2½ miles from Fort Sumter—distances extraordinary for such operations—Gillmore set up eight batteries of heavy rifled cannon. In the marsh west of Morris Island, where the mud was “like liquid,” his engineers successfully emplaced a “200 pounder” to fire on Charleston; this was to be the notorious “Swamp Angel.” [Illustration: The first great breach in Fort Sumter’s walls. Left Face interior, August 20, 1863. From an original photograph by G. S. Cook. Courtesy Mrs. T. R. Simmons, Charleston.] _The First Great Bombardment of Fort Sumter_ After some experimental firing starting August 12, the bombardment of Fort Sumter began in earnest on August 17. Nearly 1,000 shells were hurled at the fort that first day; nearly 5,000 more during the week following. Even at the end of the first day it was obvious that Fort Sumter was never intended to withstand “200 pound Yankee Parrotts.” Then, 3 days later, a 13-ton monster throwing 250-pound shells was added, making 18 rifled cannon in action. Because of the range involved, the fort could not reply to the land batteries, and the monitors presented themselves only fleetingly. On the 21st, with the “Swamp Angel” in position, Gillmore demanded the evacuation of Fort Sumter and Morris Island, threatening direct fire on the city of Charleston. Gillmore’s ultimatum was unsigned, and General Beauregard was absent from his headquarters; but before confirmation could be secured, Gillmore had opened fire on the city. But little damage had been done when, on the 36th round, the “Swamp Angel” burst. Meanwhile, Beauregard had delivered an indignant reply. The bombardment of Fort Sumter continued.