1769-1822. Robert Stewart. Irish-born British politician. He took the courtesy title of Viscount Castlereagh in 1796 when his father was promoted to the rank of earl. He became the 2nd Marquess of Londonderry in the Irish peerage on the death of his father in 1821.

• Birth: June 18, 1769  
• Son of Robert Stewart, 1st Marquess of Londonderry
• Served in junior positions in the Pitt and Addington governments 
• 1807: Secretary of State for War and the Colonies in the Duke of Portland's administration. He was involved in a dispute with Foreign Secretary George Canning over the failure of the Walcheren Expedition, and the two fought a duel late in 1809, forcing both of their resignations from the government.
• 1812: Returned to the government as Foreign Secretary for ten years. He favoured a policy of continental engagement and was involved in negotiating the allied alliance at Chaumont in March 1814 and the Treaty of Paris, and represented the United Kingdom at the Congress of Vienna.
• Death: August 12, 1822

Castlereagh was extremely unpopular at home and abroad. In 1821, he began suffering from paranoia and in August 1822, he committed suicide by cutting his throat.