Monadnock was ordered to Charleston, South Carolina, on 18 January to reinforce the South Atlantic Blockading Squadron there under the command of Rear Admiral John A. Dahlgren. After the Confederates abandoned Charleston and its surrender on 18 February, Monadnocks crew took possession of the blockade runner the following day and the monitor entered Charleston Harbor on the 20th. After a stay at Port Royal, South Carolina, she steamed to Hampton Roads, Virginia, on 15 March and then up the James River where she was assigned to the James River Flotilla. By 18 March, Commander William Ronckendorff had relieved Parrott in command of the ship. On 2 April, she steamed to support the final assault on Richmond and then assisted in clearing the river of naval mines. Returning to Hampton Roads on 7 April, Monadnock was assigned to the squadron commanded by Acting Rear Admiral Sylvanus Godon, which had been established to search for the Stonewall. The French-built ship had been ordered by the Confederacy, embargoed and sold to Denmark in 1864 and resold to the Confederacy in January 1865. Delayed by rudder problems, she was en route to the United States and ultimately made landfall in Spanish Cuba on 15 May. The squadron departed two days later and put into Charleston Harbor on the 22nd to re-coal and to be reinforced by the monitor before continuing on to Havana, Cuba. They arrived on 28 May to find that the Stonewall had been temporarily turned over to the Spanish government. Monadnocks presence no longer required, she arrived at Norfolk, Virginia, on 12 June and continued onwards to the League Island Navy Yard in Philadelphia, Pennsylvania, to prepare for her impending voyage to California. Voyage around South America To prepare the monitor for the voyage, she was fitted with a breakwater to prevent head seas from battering her forward turret and tall, wooden pilot houses above the existing ones. During the trip a jury-rigged foremast was added which reportedly added to her speed. Monadnock departed on 5 October in company with the paddle frigates and and the sloop . The monitor steamed the entire way to California entirely under her own speed and the biggest problem reported was that temperatures in the fire room ranged from . Stokers collapsed daily from heat prostration and special inducements of extra pay and spirits had to be offered for men to take their place. After