"Monticello" was renamed "Star" on 3 May 1861, but resumed her original name on 23 May. Seeing immediate action, "Monticello" relieved in blockading the James River and preventing communication with the Elizabeth River on 2 May, then relieved at Cape Henry on the 8th. She engaged the batteries at Sewell's Point on May 18 and 19, then continued blockade duty until steaming up the Rappahannock to Smith's Island on 24 June. Operating with the Army on the James River above Newport News, Virginia on 5 July, she dispersed a body of Confederate cavalry. Often engaging Confederate batteries through the remainder of 1861, she was in the squadron that captured the batteries at Hatteras Inlet on 28–29 August in the first significant Union victory, one which greatly encouraged the North. She drove off Confederates attacking Union soldiers in that area on 5 October.