 This would provide the first test of the new "Passaic" class of ironclad monitor armed with the massive new 15" Dahlgren cannon, at the time the heaviest cannon mounted on a warship.The single turret of the new class contained one 11" Dahlgren in addition to the 15".On January 27, 1863 the monitor USS "Montauk," three gunboats, and a mortar schooner again engaged the fort.