MacSheehy, Bernard (Brian) (1774–1807), officer in the French army, was born in Ireland on 2 December 1774, son of Bernard MacSheehy, also a French officer, and his wife, Honora (née Fagan). He was the fourth generation of his family (which had roots in Co. Kerry) to serve in the French army. His great-great-grandfather, Emmanuel MacSheehy (d. 1691), was a surgeon in James II's (qv) army in Ireland and was killed at the battle of Aughrim; his great-grandfather, John, entered the French service and was an engineer in the war of the Spanish succession; his grandfather, Bernard, was a captain in FitzJames's regiment in the Irish brigade and fought at Fontenoy (1745). This Bernard had at least three sons who served the king of France: Patrice, an officer in Dillon's regiment, John (b. 1746?), a physician to Louis XVI, and Bernard.
The Bernard (or Brian) MacSheehy who is the subject of this article was orphaned when young and depended on his physician uncle. He was a fee-paying student at the Irish college in Paris when revolution began (1789); as it progressed he became increasingly enthusiastic and rebellious. After war broke out he joined the English-speaking residents of Paris who, at White's Hotel on 18 November 1792, signed an address congratulating the French nation on its victories. When he joined the French army is unclear. He was appointed to the staff of General Félix Dumuy and was to have been an interpreter on his planned expedition to the East Indies (May 1794). He was also to have acted as an interpreter with a French force led by Jean Joseph Humbert (qv) which was to land in Cornwall, and for a while he was secretary to General Jacques Hatry, commander of Paris. He was appointed capitaine adjoint on the staff of General Lazare Hoche (30 June 1796).
MacSheehy's opportunity to show his abilities came when he was ordered by Hoche, whose expedition to Ireland was almost ready to leave, to go secretly to Ireland to liaise with United Irish leaders (November 1796). In this he was instructed by Theobald Wolfe Tone (qv), who, however, regarded him as a ‘blockhead’. Leaving Brest on an American ship, disembarking at Portsmouth, and travelling via London and Holyhead, he arrived in Dublin on 26 November, where he met Oliver Bond (qv), Richard McCormick (qv), and William James MacNeven (qv), from whom he obtained information on the state of the government's forces and of the pro-French party, as well as advice on the policy France should adopt towards Ireland. On his return to Brest (18 December) he found that Hoche's expedition had left three days before. His reports, which give precise information on the preparedness of Dublin Castle to resist a French invasion and of the armed United Irish to support one, are of more interest to historians than they were useful to Hoche. The United Irish leaders in Dublin benefited from his mission – they learned of the activities of Tone in France and perhaps something, at least, of the preparations being made at Brest for a French invasion of Ireland.
Despite Tone's still poor opinion of him, MacSheehy was his adjutant on the Rhine and in Normandy (April 1797 to May 1798). He left Tone to join Bonaparte's expedition to Egypt. After leaving Toulon he raised a Maltese legion that was incorporated in the main force. He was at the siege of Cairo and the recapture of Suez, for this obtaining promotion to adjutant commander (21 February 1800). Back in Europe (1801) he was regarded by the French government as an expert on Irish affairs and may even have visited Ireland (1802–3). When Bonaparte, as first consul, issued a decree for the formation of an Irish legion (31 August 1803) it was MacSheehy, appointed adjutant general, who was charged with its organisation. He proved a poor choice. He was on bad terms with Arthur O'Connor (qv), who was placed over him with the rank of general (23 February 1804), and he was the cause of at least two duels among his officers, in one of which Thomas Corbet (qv) was killed. Eventually the command was removed from MacSheehy (18 September 1804). In the opinion of his fellow officer in the French army Miles Byrne (qv), he was ‘capricious, passionate and vindictive’ and ‘not impartial as a chief should be’. MacSheehy met his death on the battlefield at Eylau on 8 February 1807, killed by a cannonball.