Trench, Richard Le Poer (1767–1837), 2nd earl of Clancarty , 1st Viscount Clancarty (UK), politician, diplomat, was born 18 May 1767 at Garbally, Co. Galway, second but first surviving son of William Power Keating Trench (1741–1805), MP for Co. Galway 1768–97 and later 1st earl of Clancarty, and Anne Trench (née Gardiner). Educated at Loughborough House School in England, he entered St John's College, Cambridge (1785), and Lincoln's Inn (1788); he was called to the Irish bar in May 1793. Deciding on a career in politics, he was elected to the Irish house of commons as MP for Newtown Limavady, Co. Londonderry (1796–7); he then sat for Co. Galway (1797–1800). Although a supporter of the government, he opposed the legislative union when it was first proposed in 1799. However, after the intervention of Lord Castlereagh (qv), who admired Trench's abilities and soon struck up an enduring friendship, he was persuaded to support the measure when it was reintroduced in 1800. With the creation of the United Kingdom he sat for Co. Galway in the united parliament (1801–5), and was returned, but never sat, for Rye in 1807. His father, who had been raised to the Irish peerage in 1797 as Baron Kilconnel of Garbally, was created Viscount Dunlo (3 January 1801) and earl of Clancarty (11 February 1803). As a result, in 1803–5 Trench was styled Viscount Dunlo, and was rewarded for his support of William Pitt when he was appointed a commissioner at the board of control (1804–6). On the death of his father (27 April 1805) he succeeded as 2nd earl of Clancarty, and entered the house of lords in December 1808 as one of the Irish representative peers, having taken the additional name of Le Poer on 27 October 1807. He served as postmaster general for Ireland (1807–9), president of the board of trade (1812–18), master of the mint (1812–14), and joint postmaster general for the UK (1814–16).
With the appointment of his friend Castlereagh as foreign secretary in 1812, Clancarty was entrusted with some crucial diplomatic missions. He was twice ambassador to the Netherlands (1813–14, 1816–23), and accompanied Castlereagh to the congress of Vienna in 1814 with the rank of plenipotentiary. After the escape of Napoleon the following year, he was temporarily the senior British diplomat at the conference and helped draft the crucial final act. As a reward for his endeavours he was created Baron Trench of Garbally in the peerage of the UK on 4 August 1815. Further honours followed: he was made marquis of Heusden by the king of the Netherlands in 1818, and was later allowed by royal licence to assume that title in the UK. Made a GCB (1815) and GCH (1821), he became Viscount Clancarty in the UK peerage on 8 December 1823. After the death of Castlereagh (1822) he gradually withdrew from active politics. Retiring to his estates in Co. Galway, he opposed the catholic emancipation bill in 1829, despite having voiced conditional support for that cause earlier in his career. He insisted in the house of lords that the bad behaviour of the catholics convinced him that emancipation should not be granted, and he maintained this position despite a rebuke from his old friend, the duke of Wellington (qv).
He died 24 November 1837 at Kinnegad, Co. Westmeath. He married (9 February 1796) Henrietta Margaret Staples; they had three sons and four daughters. His eldest son, William Thomas Le Poer Trench, succeeded him as 2nd Viscount Clancarty.