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Mordaunt, Sir Johnlocked

  • Clive Towse

Mordaunt, Sir John (1696/7–1780), army officer, was the eldest son of Lieutenant-General Harry Mordaunt (1663–1720), MP and treasurer of the ordnance, a brother of Charles Mordaunt, third earl of Peterborough, and his first wife, Margaret (1674–1706), illegitimate daughter of Sir Thomas Spencer, third baronet, of Yarnton, Oxfordshire. He entered the army in 1721, and became captain in the 3rd dragoons in 1726 and captain and lieutenant-colonel in the 3rd foot guards in 1731.

About this time Mordaunt also began a parliamentary career, as MP for Pontefract from February 1730 to 1734, in the interest of John Monckton, first Viscount Galway. He later (from 1735) represented Whitchurch, Hampshire, in the gift of John Wallop, Viscount Lymington, and from 1741 Cockermouth, where he acted as political guardian for a succession of young heirs to the Lawson family, into which his sister had married. A staunch whig, Mordaunt was a strong supporter of Robert Walpole, and was especially active during army debates. By June 1744 he had risen to the rank of colonel of the 18th foot, and was sent to Flanders as part of the British force assembled to meet the French invasion of the Netherlands. The allied army, commanded by William Augustus, duke of Cumberland, suffered defeat at Fontenoy in May 1745. Having been recalled in November and promoted brigadier-general, Mordaunt was sent against the Jacobite rising in Scotland. At Falkirk, Mordaunt rallied the scattered battalions and corps after the defeat of the government forces.

During the decisive battle of Culloden in April 1746 Mordaunt commanded the reserve. After the battle he was detached with 900 volunteers to pursue the fleeing rebels. For these actions Cumberland later presented him with Charles Edward Stuart's coach, on condition that he drove to London with it: 'That I will, sir,' he replied, 'and drive on till it stops at the Cocoa Tree'—a well-known tory haunt (Walpole, Corr., 9.35).

The following year (1747) Mordaunt was appointed major-general and colonel of the 12th dragoons, and he distinguished himself at the battle of Laffeldt in July. In 1749 he was made colonel of the 4th Irish horse, and moved later that year to the 10th dragoons. Following the end of the war Mordaunt was appointed KB, and he became one of the inspecting generals. In 1752 he was appointed governor of Sheerness. In peacetime Mordaunt revealed his relaxed nature—James Wolfe, then a lieutenant-colonel and in love with Mordaunt's niece Elizabeth Lawson, described a stay at Mordaunt's home, Freefolk, near Whitchurch, in July 1754: 'Sir J. Mordaunt's civility, good breeding and good humour make his house easy and pleasant to his guests' (Willson, 237).

The outbreak of the Seven Years' War in January 1756 immediately brought intelligence of a plan for an invasion of England, and with it the chain of events which would lead to the expedition against Rochefort which would define Mordaunt's lasting reputation. A number of army camps were set up in southern England to meet the threat, with Mordaunt commanding the camp at Blandford. In this situation, and with the war in North America going badly, it was felt that Great Britain needed to deliver a powerful counterstroke to regain the initiative. In the earliest phase of the war the prime minister, Thomas Pelham-Holles, duke of Newcastle, had proposed a diversionary raid, mentioning a number of possible objectives including Minorca, Corsica, St Domingo, Luxembourg, or the French coast itself. In November 1756, following the formation of the ministry of William Cavendish, fourth duke of Devonshire, with William Pitt as secretary of state for the southern department, the cabinet wished to support Cumberland's campaign in Germany without engaging additional British troops in the field. Sir John Ligonier, lieutenant-general of the ordnance and most senior army officer after Cumberland, had earlier in the year received a report from Lieutenant Robert Clerk, an engineer, which drew attention to the meagre defences of the naval base at Rochefort. On a visit in 1754 he had judged that the French town had inadequate fortifications, only an incomplete rampart about 25 feet high with a dry ditch protecting the town. The idea of a diversionary attack on Rochefort was supported by Pitt, who took the lead in arranging the flotilla. An additional factor which further favoured the choice of Rochefort was Ligonier's belief that there were a number of disaffected Huguenots in the area.

By the summer of 1757 a cabinet committee attended by Ligonier had accepted Clerk's report. Mordaunt was personally selected by George II to command the expedition, supported by Henry Seymour Conway and Edward Cornwallis. Both Mordaunt and Conway doubted whether the attack on Rochefort could succeed, and their fears were shared by the naval commanders Admiral Sir Edward Hawke and Vice-Admiral Sir Charles Knowles. Ligonier endeavoured to overcome Mordaunt's doubts, acknowledging that where 'neither the country nor the number of troops you are to act against is known with any precision a good deal must be left to fortune' (Whitworth, 221). However, he was confident that there were only 10,000 or fewer defending the western coast of France, and that the expedition was unlikely to be overwhelmed. Mordaunt and Conway remained unhappy—a ‘tip and run’ strategy held no appeal for contemporary army officers who preferred the set-piece tactics in progress in Germany—but with the political will behind the scheme they, Hawke, and Knowles eventually accepted the plan.

Pitt's instructions stated that the force was to take Rochefort if practical, and that it might venture to attack other French ports on its return. It was required to return by the end of September. Following the news of the defeat of Cumberland at Hastenbeck on 26 July, and the deployment of forty French battalions in Flanders, a French invasion was viewed as a real threat. After numerous delays the force, which consisted of thirty-one warships, forty-nine transports, and ten battalions of soldiers, sailed from the Isle of Wight on 6 September, and reached the Basque Roads on the 21st. The fleet was at first becalmed, but two days later captured the Île d'Aix, which guarded the mouth of the River Charente on which Rochefort lay. The two services were generally in agreement about where to land along the Bay of Chatelaillon, but a factor unconsidered in London now arose: shallow water would prevent the troop transports and naval vessels from approaching within a mile and a half of the shore. Mordaunt called a council of war on board the Neptune on 25 September. The meeting, which lasted all day, included a further report from Clerk, now a lieutenant-colonel, which suggested that Rochefort's defences could have been improved since 1754. Neutral ships also reported French preparations for British attack. The assembled senior officers of both services declared unanimously that an assault on Rochefort was 'neither advisable nor practical' (London Magazine, 651–2). Time was running out for the expedition as the equinox was expected to bring a prevailing westerly wind, which could generally delay or impede the fleet's movements. After two more days' reconnaissance and offers from General Conway to attempt a feint towards the Île de Ré or lead a real assault against the Île d'Oleron or Fort Fouras, Mordaunt summoned another council of war on the Ramillies on 28 September. This meeting unanimously decided to make a night attack on the forts at the mouth of the Charente. Mordaunt placed himself in the first embarkation. At the last moment naval officers called off the operation, as a strong wind from the shore threatened to hamper the longboats and prolong the embarkation. The tensions inherent in a divided command surfaced on the following day, when Hawke declared in a written note his intention of immediately sailing for England in default of any further military plans. A meeting of the land officers could only concur. The fleet set sail on 1 October and began arriving in Portsmouth on the 6th—with no new incursions upon the French coast.

The news of the failure of the expedition was received with fury by Pitt. The common council of the City of London demanded an inquiry. The cost of the expedition had been upwards of a million pounds. Mordaunt found he was in disgrace at court and also pressed for a formal hearing. George II instituted a board of three senior army officers: Charles Spencer, third duke of Marlborough; Lord George Sackville; and John Waldegrave. Witnesses included Mordaunt, Conway, and the expedition's quartermaster-general, James Wolfe. However, the board's report found 'It does not appear to us that there were then, or at any time afterwards either a Body of Troops or Batteries on the Shore sufficient to have prevented the attempting a Descent' (Report of the General Officers, 60). The board added that it rejected the notion that Rochefort's defences could have been so improved to have prevented any assault.

The findings of the general officers inevitably entailed a court martial. Mordaunt's trial took place from 14 to 20 December 1757. He remained confident of acquittal. His initial instructions had left much to his discretion. The charge of disobedience was unsustainable and he was unanimously acquitted. George II reluctantly confirmed the verdict. Nevertheless, the following July he struck the names of Mordaunt, Conway, and Cornwallis from the staff. Mordaunt also lost his post as governor of Sheerness.

Mordaunt remained in the army, but after Rochefort never again held a senior command in the field. He retired from the Commons in 1768. He became a full general in 1770 and was governor of Berwick from 1778 until his death. He died at Bevis Mount (his home from the mid-1750s), near Southampton, on 23 October 1780, aged eighty-three. He never married. He was buried on 28 October 1780 at St Mary's, Southampton. At the time of his death he was second general in the army list.


  • J. S. Corbett, England in the Seven Years’ War: a study in combined strategy, 2 vols. (1907)
  • H. Walpole, Memoirs of King George II, ed. J. Brooke, 3 vols. (1985)
  • [C. S. Marlborough and others], The report of the general officers, appointed … to inquire into the causes of failure of the late expedition to the coasts of France (1758)
  • Proceedings of the general court martial (1758)
  • A. Collins, The peerage of England, ed. B. Longmate, 5th edn, 8 vols. (1779)
  • W. K. Hackmann, ‘The British raid on Rochefort, 1757’, Mariner's Mirror, 64 (1978), 163–75
  • R. Middleton, The bells of victory: the Pitt–Newcastle ministry and the conduct of the Seven Years' War, 1757–1762 (1985)
  • R. Whitworth, Field Marshal Lord Ligonier: a story of the British army, 1702–1770 (1958)
  • R. R. Sedgwick, ‘Mordaunt, John’, HoP, Commons, 1715–54
  • The life and letters of James Wolfe, ed. H. B. Willson (1909)
  • L. B. Namier, ‘Mordaunt, Sir John’, HoP, Commons, 1754–90
  • GM, 1st ser., 50 (1780), 495
  • London Magazine, 26 (1757), 651–3
  • W. A. Shaw, The knights of England, 1 (1906), 169
  • parish register, Southampton, St Mary's, 28 Oct 1780 [burial]


  • BL, letters to Sir Thomas Robinson, Add. MSS 23827–23829


  • B. Dandridge, oils, 1735, Althorp, Northamptonshire
H. Walpole, ed. W. S. Lewis & others, 48 vols. (1937–83)
Gentleman's Magazine
R. Sedgwick, ed., , 2 vols. (1970)
L. Namier & J. Brooke, eds., , 3 vols. (1964); repr. (1985)