"Cumberland" recommissioned as a flagship under Captain George Henry Seymour as the flagship of his father, Vice-Admiral Sir George Francis Seymour. She served on the North America and West Indies Station. In March 1854 she sailed to the Baltic Sea as the Crimean War with Russia was imminent. "Cumberland" was involved in the Battle of Bomarsund, an Anglo-French attack on Bomarsund in the Grand Duchy of Finland in August 1854. On 15 March 1858, "Cumberland" ran aground on an uncharted rock in the River Plate off the Isla de Flores, Uruguay. Her captain and master were both acquitted at the subsequent court martial held on board at HMNB Devonport on 11 August.