Sir R. Southwell: ‘He is a young man with a very handsome face, a good head of hair, a pretty big voice, well set, and a good round leg. He pleaseth me exceedingly, being very good natured, talking freely, asking many questions, and humouring the answers. He rides the great horse very well; is a good tennis player, fencer, and dancer. He understands music, and plays on the guitar and lute; speaks French elegantly, reads Italian fluently, is a good historian, and so well versed in romances that if a gallery be full of pictures or hangings he will tell the stories of all that are there described. He shuts up his door at eight o'clock in the evening, and studies till midnight. He is temperate, courteous, and excellent in all his behaviour.’ The heir of a great house, with such endowments, soon became the darling of society. As late as 20 Feb. 1655 he was at full liberty; on that day he was at the Swedish ambassador's (Whitelocke, p. 621). But his unconcealed sympathies with the royal cause roused the jealousy of Cromwell, who, in March 1655, sent a guard to secure him. He was out at the time, but Lady Ormonde promised that he should wait upon Cromwell next morning. This, though offers were made to assist him in escaping, he did, and was sent to the Tower, although Cromwell had shortly before given him a pass to travel through Italy and the Holy Land. Ossory remained in the Tower eight months, during which his mother in vain appealed to Cromwell for his release or for information as to his crime. In October he fell ill of ague, and was partially released, but not finally freed until the following spring, when he accompanied Lady Ormonde to Acton in Gloucestershire, and later went with his brother to Flanders, apparently in disguise. Thence he went to Holland, and avoided the refugee court of Charles, lest he should give Cromwell a pretence for taking away his mother's estate. Here he stayed four years, became acquainted with the Lord of Beverwaert, the governor of Sluys, a nobleman allied in blook to the Prince of Orange, and married his eldest daughter Emilia on 17 Nov. 1659. Ormonde himself was present at the wedding, and approved the match. He hoped that by its agency he might induce De Witt, a great friend of Beverwaert, to enter heartily into the design of the king's restoration. To secure this marriage, Ossory's mother was compelled to give up 1,200l. a year out of the 2,000l. a year settled upon her by Cromwell. The father of the bride gave 10,000l. dowry, with which Ormonde's sister was to have been married and his brother John educated; but the money appears to have been immediately devoted to the necessities of the royal service. Ossory's relations with his wife were of the purest kind, and he appears to have lived without even a suspicion of libertinism. Lady Ossory ‘was an excellent woman, had exceeding good sense, and the sweetest temper in the world.’ Ossory fell into one of the court follies, that of gambling; and it is said that when, ‘after losing, he came home thoughtful and out of humour, and upon her inquiring the reason told her that he was vexed at himself for playing the fool and gaming, and that he had lost one thousand pounds, she still desired him not to be troubled—she would find ways to save it at home. She was indeed an admirable economist, always cheerful, and never known to be out of humour; so that they lived together in the most perfect harmony imaginable.’ By this marriage he became united with Henry Bennet [q. v.], earl of Arlington, already an intimate friend, who married Isabella, his wife's sister, in 1666.
At the Restoration Ossory accompanied Charles. He was already the valued friend not merely of young gallants like himself, but of the best men of the time. On 6 July 1660, for instance, Evelyn speaks of him as his ‘excellent and worthy noble friend, my Lord Ossory,’ and frequently mentions him in terms of enthusiastic admiration; while the confidence reposed in him by James is shown by the fact that he was one of the two witnesses to the duke's marriage with Anne Hyde (Hist. MSS. Comm. 5th Rep. 159). On 8 Feb. 1660–1 he was made by patent colonel of foot in Ireland, on 13 June following colonel and captain of horse, and on the 19th of the same month lieutenant-general of the horse. At the ceremony of the coronation he was one of the young noblemen appointed to bear the king's mantle, and as such he challenged the place before Lord Percy, the eldest son of the Duke of Northumberland. His pretension, which gave great offence, was unjustifiable, as Ormonde's dukedom was only an Irish one, and it was overruled by the king (Clarendon, Life, 194). In the beginning of 1662 he succeeded the Earl of Mountrath in various military commands, and on 16 Aug. 1665 was appointed lieutenant-general of the army in Ireland.
Meantime Ossory had been elected M.P. for Bristol (8 May 1661), and was also M.P. for Dublin University in the Irish House of Commons 1661–2. On 22 June 1662 Charles ordered that he should be called to the House of Peers in that country. By special order of the commons he was accompanied by Sir