Castlereagh, Robert Stewart, Viscount, 2nd marquess of Londonderry

Castlereagh, Robert Stewart, Viscount, 2nd marquess of Londonderry (1769–1822). Castlereagh outgrew his background in Ulster politics and became an advocate of the union between Britain and Ireland, a capable war secretary, and finally a distinguished foreign secretary. He entered the Irish House of Commons in 1790, soon felt drawn to the policies of the younger Pitt, and was elected to the Westminster Parliament in 1794. Castlereagh sympathized with reform in France but was unhappy about the decline of the French Revolution into violence, and was anxious about the impact of Jacobin ideas in Ireland through the secret society the United Irishmen. He supported the war against France, became prominent in the suppression of the Irish rebellion of 1798, and bore the main burden in carrying the Irish Act of Union in Dublin. He supported catholic emancipation, and resigned with Pitt when George III thwarted it. He served however in Addington's administration from 1802 and in Pitt's second ministry in 1804. On the death of Pitt he left office but became war secretary in the Portland ministry. The Peninsular War was supported by Castlereagh from the start and he took the initiative in bringing Wellesley (Wellington) forward. The failure of the Walcheren expedition meant that Castlereagh left the war department as the scapegoat. The decision to withdraw was a bitter one, the more so because Canning was eager to ensure that Castlereagh carried the responsibility for failure. The result was the collapse of the Portland ministry and the duel with Canning, which relegated both men to the back benches for several years.

Castlereagh's great opportunity came when he was appointed foreign secretary and leader of the House of Commons on the formation of Liverpool's ministry in 1812. He built up the final coalition against Napoleon, and at Vienna did much to frame the peace settlement. He was committed to regular meetings of the powers in congress not in order to perpetuate the status quo, but to enable peace to be preserved by adjustment to inevitable change. Castlereagh became alienated from Metternich and by 1820 had dissociated Britain from the Holy Alliance, which he had condemned as ‘a piece of sublime mysticism and nonsense’. Although his distrust of Russian expansion in the Near East drew Castlereagh closer to Metternich over the Greek revolt, he seriously contemplated the recognition of the independence of the Spanish American colonies. In 1822, worn out by overwork, he suffered a nervous breakdown and committed suicide.