Lord Castlereagh
/ˌlɔːd ˈkɑːslreɪ/
/ˌlɔːrd ˈkæslreɪ/
- born Robert Stewart (1769-1822) a British Tory politician who was responsible for the Act of Union with Ireland (1800). In 1809 he fought a duel (= a fight with guns to settle a quarrel) with his rival, Canning, and left the government. He returned as Foreign Secretary (1812-22). After the Napoleonic Wars he tried to keep the balance of power between European states.