Passaic Class Monitor
Ship's officers on the deck of a Passaic class monitor on the James River, circa 1864-65.

This ship has been identified in one published source as USS Sangamon and in another as USS Patapsco.

Note anchor chain on deck, ventilators erected over deck fittings, thin white band painted around the turret top, uneven height of the turret gunports, and Dahlgren howitzer on a field carriage.

**USS Sangamon, an 1335-ton Passaic-class monitor built at Chester, Pennsylvania, was commissioned in February 1863. During most of 1863 she served in the James River, Virginia, taking part in offensive moves up that river in July and August. In early 1864, Sangamon was transferred to the blockade off Charleston, South Carolina, but returned to the James later in the year. In March and April 1865, she took part in operations to counter the threat of Confederate ironclads and to clear mines from the river. Following the end of the Civil War, Sangamon was placed out of commission at Philadelphia, Pennsylvania. Renamed Jason in June 1869, the monitor was apparently inactive from 1865 until 1898.  Jason recommissioned in May 1898 for Spanish-American War service. Stationed on Long Island, she provided the New York area with some degree of naval protection against the perceived threat of a raid by Spanish cruisers. Again laid up at Philadelphia after the end of the conflict, USS Jason was sold in April 1904.

**USS Patapsco, a 1335-ton Passaic class monitor built at Wilmington, Delaware, was commissioned in early January 1863. Assigned to the South Atlantic Blockading Squadron, she took part in a bombardment of Fort McAllister, on Georgia's Ogeechee River, on 3 March. On the 7th of April Patapsco joined eight other ironclads in a vigorous attack on Fort Sumter, off Charleston, South Carolina, and received 47 hits from Confederate gunfire during that day. Beginning in mid-July, she began her participation in a lengthy bombardment campaign against Charleston's defending fortifications. This led to the capture of Fort Wagner, on Morris Island, in early September. Fort Sumter was reduced to a pile of rubble, but remained a formidible opponent. 

In November 1863, Patapsco tested a large obstruction-clearing explosive device that had been devised by John Ericsson. Remaining off South Carolina and Georgia during much of 1864 and into 1865, the monitor, or her boat crews, took part in a reconnaissance of the Wilmington River, Georgia, in January 1864 and helped capture or destroy enemy sailing vessels in February and November of that year.

On 14 January 1865, while participating in obstruction clearance operations in Charleston Harbor, USS Patapsco struck a Confederate mine and sank, with heavy loss of life.