Duff, Robert (17211787), naval officer, was a cousin of William Duff, first Earl Fife, and connected with the earl of Bute. Details of his parents are unknown. He was listed a lieutenant by 9 March 1739, promoted commander on 4 December 1744, and in 1746 had command of the bomb-vessel Terror on the coast of Scotland. On 23 October he was promoted captain of the new ship Anglesea (44 guns), which he commanded on the coast of Ireland and the home station until the treaty of Aix-la-Chapelle (1748). In 1755 he was appointed to the Rochester (50 guns), which was employed during the following years on the coast of France either in independent cruising or as part of the Grand Fleet. In 1758 Duff was with Commodore Richard Howe in the squadron covering the expeditions against St Malo, Cherbourg, and St Cas. In 1759 he was senior officer of the little squadron stationed on the south coast of Brittany to keep watch over the movements of the French in Morbihan, while Edward Hawke with the fleet blockaded Brest. He was lying at anchor in Quiberon Bay, his squadron consisting of four 50-gun ships and four frigates, when, on the morning of 20 November, his outlook frigate informed him of the French fleet to the south of Belle Île. Duff hastily put to sea and stood to the southward, chased by the French. Engagement was prevented by the appearance of the British fleet in pursuit of the French, who were overtaken and attacked before they could reach safety.
Duff was afterwards appointed to the Foudroyant (80 guns), a crack ship in which he accompanied Rear-Admiral George Brydges Rodney to the West Indies, and took part in the capture of Martinique during January and February 1762. However, because of his seniority he refused to serve as Rodney's flag-captain, and was sent home. In 1764 he married Helen, the daughter of his cousin the Earl Fife; they had several children.
On 31 March 1775 Duff was promoted rear-admiral, and in April he was sent out as commander-in-chief at Newfoundland. In September 1777 he was appointed to the command of the Mediterranean, with his flag in the Panther. When the siege of Gibraltar was begun in 1779, Duff co-operated with the garrison in so far as the very limited force at his disposal permitted. The government, not being able to strengthen his command, recalled him early in the following year. He had been promoted vice-admiral on 29 January 1778, but held no further command after his return to England in 1780. During his later years he was grievously afflicted with gout, his death being attributed to an attack of gout in the stomach. He died at Queensferry on 6 June 1787.
Robert Duff's grandnephew George Duff was killed at Trafalgar in command of the Mars, and before the battle had command of the inshore squadron watching the motions of the enemy in Cadiz.
J. K. Laughton, rev. Nicholas Tracy
J. Charnock, ed., Biographia navalis, 6 vols. (17948) · TNA: PRO, ADM 1/307; 30/20/8 p. 168 · D. Syrett and R. L. DiNardo, The commissioned sea officers of the Royal Navy, 16601815, rev. edn, Occasional Publications of the Navy RS, 1 (1994) · HMC
NA Scot., corresp. and papers
NMM, log books, letter books, papers | TNA: PRO, ADM 1/307, Rodney 1 July 1762; 30/20/8 p. 168