in the House of Lords. On 6 June 1810 he expressed modified approval of the catholic claims, but criticised severely the attitude adopted by the Irish catholic hierarchy since 1808. When the question was raised by Lord Wellesley two years later, he declared against unqualified concession, but was in favour of a thorough examination. On 4 Jan. 1811 Clancarty, in a closely reasoned speech, defended the resolutions restricting the powers of the regent. In November 1813 he accompanied the Prince of Orange to The Hague, and was accredited to him as English ambassador when he was proclaimed William I of the Netherlands. On 13 Dec. he wrote to Castlereagh: 'What with correspondence with two admirals, four generals, British and allied, and your lordship, I am kept so well employed that I have scarcely time to eat or sleep.' On the 14th he wrote urgently demanding the immediate despatch of Graham (Lord Lynedoch) with reinforcements to the Netherlands. Early in 1814 he was in communication with Lord Liverpool, the prime minister, on the subject of the Dutch finances. Clancarty was energetic in urging on the Prince of Orange the necessary military measures, and succeeded in inducing him to resign the command of the allied forces in the Netherlands to the prince royal of Sweden, Bernadotte. In the succeeding months he was chiefly engaged in formulating a plan for the incorporation of the Belgian and Dutch provinces into the proposed new state of the Netherlands (cf. Yonge, Life of Liverpool, i. 514). Other difficulties were the adjustment of financial relations and the claims of the Belgian clergy and noblesse. During the summer months of 1814 his attention was also directed towards the opening up of a reciprocal colonial trade between England and Holland, and to the resumption of negotiations for a marriage between the Princess Charlotte of England and the hereditary Prince of Orange. Meanwhile Clancarty had kept himself fully informed of the general situation of European affairs. On 11 Aug. he was named one of the four English plenipotentiaries to the congress of Vienna. Talleyrand, in a letter to Louis XVIII of 28 Dec., speaks of his zeal, firmness, and uprightness. When Wellington left Vienna for Belgium in March 1815, Clancarty became the senior British plenipotentiary. He was the British representative on the various commissions respectively appointed to delimit the Polish frontier and to adjust the affairs of Saxony (October 1814); to mediate between Sardinia and Genoa; to regulate the affairs of Tuscany and Parma, and to draw up a preliminary convention (8 Feb. 1815). On 11 March 1815, in an interesting despatch to Castlereagh, he described the consternation of the royal personages at the news of Napoleon's escape from Elba, but thought it desirable to encourage their fears with the view of bringing to an end the business of the congress. After the peace, on 4 Aug. 1815, he was created Baron Trench of Garbally in the English peerage.
At the end of the year Clancarty went to Frankfort, and was engaged in adjusting the disputes between Bavaria and Baden. On 22 May 1816 he was appointed ambassador to the new kingdom of the Netherlands, but was detained at Frankfort through the summer. During his second embassy to Holland Clancarty was at first mainly occupied in urging the king to take sufficiently strong measures against the French refugees in the Netherlands, who were plotting against the recent settlement of the country. Subsequently Clancarty devoted his attention to negotiations between Great Britain and the Netherlands for the suppression of the slave trade. During the remainder of the year he was chiefly occupied in negotiations with Prussia relating to frontier disputes and to the evacuation of the Netherlands by Prussian troops. During 1821 the conduct of the Dutch in pretending that the slave-trade convention of 1818 was confined to Africa engaged Clancarty's serious attention. On 4 Aug. Wellington arrived at The Hague, and, after Clancarty had put him in possession of the facts, had an interview with William I. The king gave satisfactory assurances. In the autumn George IV came over, and Clancarty was one of those who attended him when he visited Waterloo (Buckingham, Courts and Cabinets of George IV, i. 203).
Early in 1822 Clancarty resigned his post in the Netherlands. In 1818 he had received a pension of 2,000l., and had also been created Marquis of Heusden by the king of the Netherlands. On 8 Dec. 1823 he was advanced in the British peerage to the dignity of a viscount. Henceforth he resided usually on his estates in Ireland, where he was lord-lieutenant of co. Galway and vice-admiral of Connaught. On 8 March 1827, speaking in the House of Lords, he censured the negligence of the law officers in Ireland, and declared his opinion that no exceptional measures were necessary for repressing the Catholic Association; but in 1829, when the catholic relief bill was brought in by the government, he opposed the measure on account of the conduct of the catholics. He said that, like Pitt, he would have granted relief on condition of their good behaviour.
