In 1806 Moresby was first lieutenant of the ‘Ville de Paris’, flagship of Lord Collingwood in the Mediterranean. He remained on that station until the end of the war, commanding the ‘Wizard’ brig as a lieutenant. His services in the Adriatic, especially at the siege of Trieste, were highly commended and in 1814 he was awarded the cross of the order Maria Theresa. As senior officer at Mauritius in 1820 he was active in implementing the anti-slavery laws. His last service was commander-in-chief in the Pacific, 1850–53, when he recommended the development of a naval base at Esquimault on the west coast of Canada. He became an admiral of the fleet in 1870.

He is shown wearing admiral of the fleet’s full dress uniform 1856–79, but with admiral’s epaulettes, the star and ribbon of the Order of the Bath and the Maria Theresa cross. The portrait is inscribed, signed and dated ‘Admiral Sir Fairfax Moresby by E. A. Gifford 1870’. Gifford (active 1833–76) was an architect and amateur painter, and it seems possible that this portrait may be based on a photograph.