Robert Stewart, 2nd Marquess of Londonderry, KG, GCH, PC, PC (Ire) (18 June 1769 – 12 August 1822), usually known as Lord Castlereagh (/ˈkɑːsəlreɪ/ KAR-sul-RAY), was an Irish and British statesman. As British Foreign Secretary, from 1812 he was central to the management of the coalition that defeated Napoleon and was the principal British diplomat at the Congress of Vienna. Castlereagh was also leader of the British House of Commons in the Liverpool government from 1812 until his alleged suicide in August 1822. Early in his career, as Chief Secretary for Ireland, he was involved in putting down the Irish Rebellion of 1798 and was instrumental in securing the passage of the Irish Act of Union of 1800.His foreign policy from 1814 was to work with the leaders represented at the Congress of Vienna to provide a peace in Europe consistent with the conservative mood of the day. Much more than prime minister Lord Liverpool, he was responsible for the repressive domestic measures. Historian Charles Webster concludes:"There probably never was a statesman whose ideas were so right and whose attitude to public opinion was so wrong. Such disparity between the grasp of ends and the understanding of means amounts to a failure in statesmanship."