Robert Stewart, Viscount Castlereagh, Lord Castlereagh, 2d marquess of Londonderry (1769–1822)

Statesman. Styled Viscount Castlereagh from 1796. Chief secretary of Ireland, 1798–1801. President, (East India) Board of Control, 1802–5. Secretary of state for the War and Colonial Department, 1805; secretary of state for war, 1807–9. Foreign secretary, 1812–22. Succeeded as 2d marquess of Londonderry in 1821.