"Mount Washington" saw heaviest action in 1863 in the Siege of Suffolk, Virginia. She towed to Washington 8 January, joining the campaign in April. She found aground at the mouth of the Nampony River 13 April and learned that the Confederates planned to cross the river to attack the Union's rear forces at Suffolk, Virginia, and to silence the gunboats for this purpose. In the subsequent Battle of Suffolk at the Norfleet House Battery, "Mount Washington" exchanged artillery fire with the Confederates at Hampton Roads, 14 April, meeting sharp musketry. Four sailors temporarily assigned to "Mount Washington" were awarded the Medal of Honor for their actions during this battle: Coxswain Robert Jordan, Seaman Henry Thielberg, Coxswain Robert B. Wood, and Seaman Samuel Woods. Later in April, she and "Stepping Stones" were fired on at Norfleet's Point. Towing "West End" downriver, "Mount Washington" ran aground but moved off with the next high tide. Four Negroes boarded her a few days later, reporting no sign of Confederates; nevertheless, "Mount Washington" was fired on moments later, and a severe engagement ensued.