CAHIDEUC, EMMANUEL-AUGUSTE DE, Comte DUBOIS DE LA MOTTE, naval officer; b. 1683 in Rennes, France, son of Jean-François de Cahideuc, Comte Dubois de La Motte, and Gilonne-Charlotte de Langan; m. Jeanne-Françoise d’Andigné de La Chaise, by whom he had two sons; d. 23 Oct. 1764 in Rennes.
Emmanuel-Auguste de Cahideuc joined the service as a midshipman at Brest on 8 Nov. 1698. After serving on several ships in the Atlantic and the Mediterranean, on 1 Nov. 1705 he was promoted sub-section leader in the midshipmen. He then served as a lieutenant in the grenadiers at the siege of Gibraltar, and later as adjutant of the coastal defence batteries at Saint-Malo. In 1706 he sailed on the Dauphine and campaigned brilliantly in the English Channel and the Atlantic. Having transferred to the Achille in René Duguay-Trouin’s squadron in 1707, he took part in the engagement on 21 October which inflicted heavy losses on a large English convoy. The following year he took command of the privateer Argonaute, with which he conducted a new and profitable campaign at the entrance to the English Channel and in the Atlantic. On 10 Jan. 1708 he was promoted section leader in the midshipmen, and on 13 Feb. 1709 he received the rank of sub-lieutenant. Befriended by Duguay-Trouin, Dubois de La Motte accompanied him in the successful expedition against Rio de Janeiro in September 1711, and distinguished himself at the head of a grenadier company.
The peace which followed the treaty of Utrecht in 1713 caused a reduction in the number of ships in commission; as a result, Dubois de La Motte had a long period of service ashore at Brest. Promoted lieutenant-commander on 17 Aug. 1727, he was made captain on 1 April 1738. He cruised off Ireland in 1744 and conducted three successful campaigns in the West Indies in 1740–41, 1745, and 1746. In the last campaign his skilful manoeuvres ensured the safe arrival in France of the 163 merchant ships for which he was responsible. On 1 Jan. 1751 he was promoted rear-admiral and governor general of Saint-Domingue (Hispaniola). He remained there two years.
The Seven Years’ War was to give Dubois de La Motte new opportunities to distinguish himself. In 1755 he received command of the Entreprenant and a squadron of 15 ships of the line and four frigates, with which he was instructed to take help to Canada. He sailed from Brest on 3 May and reached his destination, but on 10 June two of his ships, the Alcide and the Lys, which had been separated from the squadron by fog, had been attacked and captured by Edward Boscawen’s fleet, although war had not been declared. Dubois de La Motte left for France on 15 August, and to elude the enemy he daringly sailed all his vessels through the Strait of Belle Isle, a route which no king’s ship had ever taken. Thanks to this adroit manoeuvre, the return voyage was without mishap.
On 25 Nov. 1755 he was promoted lieutenant-general of the naval forces, and at the beginning of 1757 he was given command of a squadron of nine ships of the line and two frigates with which to reinforce the defences of Louisbourg, Île Royale (Cape Breton Island). He arrived there on 19 June, and soon received additional strength in the form of five ships of the line and a frigate from Saint-Domingue under Joseph de Bauffremont, and four ships and two frigates from Toulon under Joseph-François de Noble Du Revest. Dubois de La Motte with this concentration of forces at his disposal was able to deploy before the citadel such an intimidating defence that the English squadron under Francis Holburne did not dare attack, and on 24 September it was scattered by a gale. But lack of supplies and a typhus epidemic prevented Dubois de La Motte from pursuing the English fleet and forced him to return to France. He left Louisbourg on 30 October and reached Brest safely on 23 November, landing about 5,000 sick men there. His activity had delayed the fall of Île Royale by a year.
Dubois de La Motte’s active naval career was ended, but in September 1758, when the English landed near Saint-Malo, he went there despite his 75 years and took part in the battle which repulsed the enemy. He had been made a knight of the order of Saint-Louis on 17 Dec. 1718, commander on 1 Sept. 1752, and knight grand cross on 4 July 1761. On 13 Dec. 1762 he was promoted vice-admiral. An expert seaman, a daring, methodical, and thoughtful leader, Dubois de La Motte was one of the finest figures in the French navy of his time.
AN, Col., C9A, 90, 92, 94; Marine, B4, 27, 31, 32, 34, 35, 36, 42, 43, 50, 56, 57, 59, 61, 68, 74, 76, 78; C1, 161; 165; 166, f.28; C7, 90 (dossier Dubois de La Motte); G, 38, f.10. DBF, VII, 830. Étienne Taillemite, Dictionnaire de la marine (Paris, 1962), 78. Étienne Taillemite et al., Tables des noms de lieux, de personnes, de matières et de navires, sous-série B1, B2 et B3 (Paris, 1969), 101. Lacour-Gayet, La marine militaire sous Louis XV (1910), 119, 200, 252, 383, 487, 530. Troude, Batailles navales de la France, I, 246, 249, 259, 271, 319, 326. Société historique et archéologique de l’arrondissement de Saint-Malo, Annales (Saint-Servan), 1940, 145–46.