O'Mahony, Daniel (d. 1714), ‘le fameux O'Mahoni’, soldier and hero of Cremona, was born in Dromore, Co. Kerry, son of Dermod (Danby) O'Mahony and his wife Mary (née Moriarity). Little is known of his early life. He served as a captain in King James's (qv) Royal Irish footguards (in which his brother Dermod was a colonel who distinguished himself at the Boyne, Limerick, and Aughrim, where he met his death). Daniel went to France in 1692, served as major of the Limerick and Dillon regiments, and became a well placed officer at the exiled court; the future ‘James III’ acted as a godfather to his eldest son James Joseph in November 1699.
O'Mahony served under Marshal Villeroi in northern Italy in 1701, in command of a detachment of Gen. Dillon's regiment, in the absence of Col. Gerald Lally. It was at this time that he performed his greatest service to the French army in Italy. At the beginning of February 1701 the city of Cremona was betrayed to the imperial commander Prince Eugene, ‘the Atlas of the Holy Roman Empire’. His forces stormed into Cremona at night, surprised the French garrison, and captured Villeroi. O'Mahony rallied his Irishmen at the Po gate, and despite murderous fire and bribes refused to desert his post. By his victory he added to the growing reputation of the Irish regiments in Europe. Indeed, the erstwhile Jacobite Charles Forman stated that ‘the Irish performed the most important service for Louis XIV that perhaps any king of France had ever received from so small a body of troops’, adding that their action ‘by an impartial way of reasoning saved the whole of the French army in Italy’ (O'Callaghan, Irish brigades, 216).
O'Mahony was afforded the privilege of bringing the news of the loss and recapture of Cremona to the grateful Louis XIV, who gave him an hour-long audience in his bed-chamber, immediately promoted him to colonel and gave him a pension of 1,000 livres, and a present of 1,000 louis d'or to cover his expenses. O'Mahony also received a knighthood from his own monarch, James III, the Young Pretender; his heroic exploits were later immortalised by Sir Arthur Conan Doyle in ‘The day we beat the Germans at Cremona’.
O'Mahony continued to serve in northern Italy under the new French commander, Marshal Vendôme. Appointed governor of Brescello on its surrender (28 July 1703), he also took part in his commander's successes at San Sebastian and Castel Novo de Bormida. In 1704 he left the French service and took command of a regiment of deserters from the abortive British expedition to Cadiz. In 1704–5 he served with distinction under the prince de Tilly and was promoted to maréchal de camp. He stormed and sacked Euguera and held Alicante against the British commander Sir John Leake. After surrender he marched out at the head of his regiment with the full honours of war. In 1707 he again took command in Valency and performed heroically at the head of his Irish dragoons under his future brother-in-law the duke of Berwick (qv) at the decisive battle of Almanza. In 1710 he became a count of Castile, and was promoted to lieutenant-general and given command of the Franco–Spanish army. Philip V finally rewarded his invaluable services to the Bourbon cause with the commandership of the order of St Iago de Compostella. O'Mahony died in Ocaña in January 1714, fighting under the command of Berwick.
O'Mahony married first Celia, daughter of George Weld of Lulworth, Dorset, England. On her death he married (28 May 1708) Charlotte Bulkeley, sister of the duchess of Berwick and widow of his illustrious compatriot Charles O'Brien (qv), 5th Viscount Clare. After count O'Mahony's death his descendants continued to hold high office in Spain and the Two Sicilies. His younger son Dermot (d. 1776) became Spanish ambassador to Vienna; James Joseph was inspector-general of cavalry in the service of Naples and his daughter Mary Anne married the count's friend and compatriot, the economist Richard Cantillon (qv).
The diarist Saint-Simon says that O'Mahony was ‘a man of wit as well as valour’ (DNB). Another contemporary, the chevalier de Bellerie, claimed that O'Mahony was ‘not only brave but indefatigable and very painstaking’, and that his life was ‘a continual chain of dangerous combats, of bold attacks and honourable defeats’ (O'Callaghan, Irish brigades, 205). O'Mahony's military papers and correspondence survive in the Archives Nationales, Fonds Guerre, Paris.