USS Passaic, first of a ten-ship class of 1335-ton ironclad monitors, was built at Greenpoint, New York. Commissioned in late November 1862, she was detained at Washington, D.C., for repairs during much of December. After a difficult passage through the storm that sank USS Monitor, she reached Beaufort, North Carolina, on 1 January 1863 and later in the month moved on to Port Royal, South Carolina, where she joined the South Atlantic Blockading Squadron.

Passaic's combat service began on 23 February 1863, in Wassau Sound, Georgia, where she took part in the capture of a blockade-running schooner. On 3 March, during an intended "shakedown" operation for new monitors, she bombarded Fort McAllister, on Georgia's Ogeechee River. Passaic was one of nine ironclads that attacked Fort Sumter, off Charleston, South Carolina, on 7 April 1863. She received serious damage at that time and had to go to New York for repairs.

Returning to the war zone in late July, Passaic kept busy over the next two months bombarding Confederate fortifications at the harbor entrance. Among other contributions, her gunfire helped to reduce Fort Wagner, on Morris Island, facilitating its capture in early September. Passaic spent the remainder of the Civil War operating in South Carolina and Georgia waters. Returning north after the conflict's end, she decommissioned at Philadelphia, Pennsylvania, in June 1865.

After more than a decade in reserve, Passaic recommissioned in November 1876. She was receiving ship at the Washington Navy Yard, D.C., in 1878-82, then was assigned to the U.S. Naval Academy, Annapolis, Maryland, during 1883-92. The now-elderly monitor was employed on Naval Militia service in Massachusetts and Georgia during much of the rest of the 1890s and recommissioned in May 1898 for Spanish-American War duty. After a brief tour in Florida waters, she was decommissioned for the last time in September 1898. USS Passaic was sold in October 1899.