Luc Urbain de Bouëxic, comte de Guichen (June 21, 1712, Fougères, Ille-et-Vilaine – January 13, 1790, Morlaix) was a French admiral who commanded the French fleets that fought the British at the First Battle of Ushant (1778) and the Battle of Martinique (1780) during the American War of Independence.
Guichen entered the navy in 1730 as "garde de la Marine," the first rank in the corps of royal officers. His promotion was not rapid. It was not till 1746 that he became "lieutenant de vaisseau", which was, however, a somewhat higher rank than the lieutenant in the British navy, since it carried with it the right to command a frigate. He was promoted "capitaine de vaisseau", or post captain, in May 1756. But his reputation must have been good, for he was made chevalier de Saint Louis in 1748.
In that year, 1748, de Guichen had fought no fewer than five battles against superior British forces, while escorting back to France, from the Antilles a huge convoy. In 1755 he participated in the abortive relief expion to Louisbourg under Dubois de La Motte, and was involved, onboard L'Heros 70 off Louisbourg. In 1775 he was appointed to the frigate Terpsichore, attached to the training squadron, in which the duc de Chartres, afterwards notorious as the duc d'Orléans and as Philippe Egalité, was entered as volunteer. In the next year he was promoted Chef d'Escadre, or Rear-Admiral. 
When France had become the ally of the Americans in the War of Independence, he hoisted his flag in the Channel fleet, and was present at the battle of Ushant on 27 July 1778, where his flagship, La Ville de Paris (90 guns) took station just abaft the fleet-flagship, La Bretagne, and several times fought off both Keppel, Palliser and other determined English assailants. For this deed he and his crew received the 'Cordon Rouge' for outstanding valour. In March 1779 he was promoted Lieutenant Général des Armées Navales, or roughly corresponding to the British Vice-Admiral of the White and Red and Admiral of the Blue and White. As such he commanded the French van in the Combined fleet of Comte d'Orvillers and Don Luis de Córdoba y Córdoba that year (June–September).
In January 1780 he was sent to the West Indies with a strong squadron and was there opposed to Sir George Rodney. In the first meeting between them on April 17 to the leeward of Martinique, Guichen escaped disaster only through the clumsy manner in which Sir George's orders were executed by his captains. But, thanks to the orderly fashion in which his own subordinate squadron-commanders dealt with the crisis, especially the third-in-command François-Joseph Paul, Comte de Grasse-Tilly's rapid closing-up of the battle-line, de Guichen managed to extricate himself from a difficult situation and, instead turn the Battle of Martinique from a narrow defeat to a draw. still, his and Marquis de Bouillé's plan to attack and seize Jamaica was cancelled.
During the battle of Martinique, both Rodney's Sandwich (90 guns) as well as de Guichen' own La Couronne (80 guns) had been temporarily cut off from their respective fleets and had borne the brunt of the battle. Realizing he had to deal with a formidable opponent, de Guichen acted with extreme caution, and by keeping the weather gauge afforded the British admiral no chance of bringing him to close action.
The following two actions, on 15 and 19 May, also off Dominica and Martinique, were set-pieces of masterly fleet handling that Rodney could not parallel. Although the French had the better of both, the battles were inconclusive. In conjunction with the battle of the 17 April, these three battles are called Les Trois Combats de Mons. de Guichen in the French naval annals.
When the hurricane months approached (July to September) Guichen left the West Indies, and his squadron, being in a bad state from want of repairs, returned home, reaching Cadiz in September, bringing with him a convoy of 95 merchants. On that roadstead his able second-in-command, H.-A., Comte de Sade, a maternal cousin of the infamous 'Marquis' de Sade, died at age 69. Previously Guichen, himself had suffered a personal loss, by the death of his eldest son, Luc, Chevalier de Guichen, through tropical fever.
David Hannay, the author of the biography on the Comte de Guichen in the 11th ion of the Encyclopædia Britannica stated that throughout all this campaign Guichen had shown himself very skillful in handling a fleet, and if he had not gained any marked success, he had prevented the British admiral from doing any harm to the French islands in the Antilles.
In December 1781 the comte de Guichen was chosen to command the force which was entrusted with the duty of carrying stores and reinforcements to the West Indies. On the 12th Admiral Kempenfelt, who had been sent out by the British Government with an unduly weak force to intercept him, sighted the French admiral in the Bay of Biscay through a temporary clearance in a fog, at a moment when Guichen's warships were to leeward of the convoy, and attacked the transports at once. The French admiral could not prevent his enemy from capturing twenty of the transports, and driving the others into a panic-stricken flight. They returned to port, and the mission entrusted to Guichen was entirely defeated. He therefore returned to port also. He had no opportunity to gain any counterbalancing success during the short remainder of the war, but he was present at the final relief of Gibraltar by Lord Howe.
The Comte de Guichen was, by the testimony of his contemporaries, a most accomplished, valorous, brave and high-minded gentleman. It is probable that he had more scientific knowledge than any of his English contemporaries and opponents. But as a commander in war he was notable chiefly for his skill in directing the orderly movements of a fleet, and seems to have been satisfied with formal operations, which were possibly elegant but could lead to no substantial result. He had none of the combative instincts of his countryman Suffren, or of the average British admiral.