First Lady Dolley Madison, Senators Thomas Hart Benton of Missouri, Nathaniel P. Tallmadge of New York, William Cabell Rives of Virginia, Samuel S. Phelps of Vermont, Spencer Jarnagin of Tennessee, Edward A. Hannegan of Indiana, and about 400 guests. Captain Stockton decided to fire the larger of the ship's two long guns, Peacemaker, to impress his guests. Peacemaker was fired three times on the trip downriver and was loaded to fire a salute to George Washington as the ship passed Mount Vernon on the return trip. The guests aboard viewed the first set of firings and then retired below decks for lunch and refreshments. Secretary Gilmer urged those aboard to view a final shot with the Peacemaker. When Captain Stockton pulled the firing lanyard, the gun burst. Its left side failed, spraying hot metal across the deck and fragmentation into the crowd. Six men were instantly killed: Secretary of State Abel Upshur Secretary of the Navy Thomas Walker Gilmer Captain Beverley Kennon, Chief of the Bureau of Construction, Equipment and Repairs Armistead, a Black enslaved person who was President Tyler's valet David Gardiner, a New York lawyer and politician Virgil Maxcy, a Maryland attorney with decades of experience as a state and federal officeholder Another 16 to 20 people were injured, including several members of the ship's crew, Senator Benton, and Captain Stockton. The president was below decks and not injured. Aftermath Rather than ascribe responsibility for the explosion to individuals, Tyler wrote to Congress the next day that the disaster "must be set down as one of the casualties which, to a greater or lesser degree, attend upon every service, and which are invariably incident to the temporal affairs of mankind". He said it should not affect lawmakers' positive assessment of Stockton and his improvements in ship construction. Plans to construct more ships modeled on Princeton were promptly scrapped. Still, Tyler won Congressional approval to construct a single gun on the dimensions of the Peacemaker, fired once and never mounted. A Court of Inquiry investigated the cause of the explosion and found that all those involved had taken appropriate precautions. At Stockton's request, the Committee on Science and Arts of the Franklin Institute conducted its own inquiry, which criticized many details of the manufacturing process, as well as the use of a welded band for reinforcement rather than the shrinking technique used on the Oregon. Ericsson, whom Stockton had