He returned to France in 1811. On the fall of the Empire he had better fortune than most of the Napoleonic officers who were turned ashore. In 1821 he became lieutenant, and in 1823 took part in the French expedition under the Duke of Angoulême into Spain. In 1828 he was appointed captain of the Acton, and was engaged till 1831 on the coast of Algiers and in the conquest of the town and country. His first command as flag officer was in the Pacific, where he showed much tact during the dispute over the Marquesas Islands with England in 1844.
He was promoted vice-admiral in 1848. During the Crimean War he commanded in the Black Sea, and co-operated with Admiral Dundas in the bombardment of Sevastopol on 17 October 1854. His relations with his English colleague were not very cordial. On 7 December 1854 he was promoted to admiral. Shortly afterwards he was recalled to France, and was named minister of marine.
His administration lasted till 1860, and was remarkable for the expeditions to Italy and China organized under his directions; but it was even more notable for the energy shown in adopting and developing the use of armour. The launch of the Gloire—the example of constructing seagoing ironclads. When Napoleon III made his first concession to Liberal opposition, Admiral Hamelin was one of the ministers sacrificed. He held no further command, and died on 10 January 1864.