This distinguished Irish soldier of fortune, the _last_ of the _eleves_ of the Lacys and others whose achievements in the third Silesian war and the Turkish campaign have already been recorded, obtained the rank of General in the Austrian army, Chamberlain, and Commander of the Imperial and Military Order of Maria Theresa, with the rank of Colonel Proprietaire of the 3rd Regiment of Light Horse. He was born in 1740, and was the second son of James O'Reilly, of Ballincough, in the county of Westmeath, and of Barbara, daughter of Thomas Nugent, Esquire, of Dysart (grand-daughter of Thomas, fourth Earl of Westmeath). His brother Hugh was created a Baronet by George III., and subsequently assumed the name of Nugent. His only sister married Lord Talbot de Malahide. Entering the Imperial service early in life, O'Reilly filled in succession all the military grades save that of Field-Marshal; but of those events in his stirring life which led to his elevation to a coronet, we barely afford a summary. One of the most important incidents in his early career is connected with his marriage; and while it illustrates the manners of the last century, is worthy of notice, for the remnant of old romance and chivalry it displays. He and a brother officer, Count Klebelsberg, uncle of Francis Count de Klebelsberg, who, in 1831, was President of the Government of Lower Austria, were rivals for the hand of the Countess Wuyrlena, a rich and beautiful Bohemian heiress; and aware that _both_ could not succeed, they determined to solve the difficulty of selection by a combat _a l'outrance_. The intended duel was, however, reported to the authorities, and both O'Reilly and Klebelsberg were placed under close arrest by the Director General of the High Police; but, resolved to achieve their purpose, they secretly left Vienna, and travelled post together to Poland, and meeting in the neutral territory of Cracow, fought their remarkable combat. The duel lasted long, for both were perfect swordsmen, active, skilful, and wary; but at length O'Reilly ran Klebelsberg through the body, after receiving many dangerous wounds in his own person. The affections of the countess, with her hand and fortune, were the immediate reward of the soldier of fortune. Rejoining the army, he served with great brilliance in the war between France and Austria. The forces of the latter were commanded by the Archduke Charles. On the 14th June, 1800, he fought under General Melas, at the battle of Marengo. "Melas," says M. Thiers, in his _History of the Consulate and Empire_, "placed General O'Reilly on the left, and Generals Kaim and Haddick on the right, to gain the road to Piacenza, the object of so many efforts and the salvation of the Austrian army."