Castlereagh Papers

Personal, family and political papers, 1798-1822 (including some earlier and some later documents), of Robert Stewart (1769-1822), Viscount Castlereagh, later 2nd Marquess of Londonderry. Elected first to the Irish Parliament in 1790 to represent Co Down and subsequently in the English Parliament from 1794-1822, Castlereagh rose to play a dominant role in British policy and politics. As acting Chief Secretary to the Lord Lieutenant of Ireland he dealt decisively with the leaders of the '98 Rebellion and was officially appointed to the Chief Secretaryship in November 1798. He devoted the next two years to promoting the passage through the Irish Parliament of legislation for the Union of Great Britain and Ireland but resigned, with Pitt, when George III refused to grant Catholic Emancipation. In 1802, he became President of the Board of Control, and Secretary for War and the Colonies in 1805-6 and 1807-9 which he resigned after the disastrous conclusion of the Walcheren expedition and his duel with the Foreign Secretary, George Canning. From 1812 until his death in 1822, he was both Foreign Secretary and Leader of the House of Commons at a time of intense military and political activity in many arenas which is reflected in the collection. He was at the heart of the coalition against Napoleon (1813-14) and represented England at Chaumont and Vienna (1814-15), Paris (1815) and Aix-la-Chapelle (1818).

The core of 'The Castlereagh Papers' comprises some 37 volumes containing 6,217 letters and papers which were arranged and bound in the 3rd Marquess's time and were selectively published under his remote editorial control as the Memoirs and Correspondence of Viscount Castlereagh (12 vols, London, 1848-1853). In addition, there are two further bound volumes containing engraved portraits of contemporary personalities with letters from them to Castlereagh and letters between Castlereagh and Lord Melville (1804-1805), letters from Castlereagh and the 1st Marquess of Londonderry to their agent, Rev. John Cleland (1790-1810) and letters between Castlereagh and the future 3rd Marquess about family settlements (1810-1822). The collection also includes papers of the Viscount’s wife, Emily, his half-brother and successor, Charles Vane, the 3rd Marquess, and the 3rd Marquess's wife, Frances Anne.


The collection is important for researchers of Catholic emancipation, home and foreign policy in the late 18th and early 19th centuries.

Physical characteristics

c. 7,490 documents and volumes, occupying 32 PRONI boxes

Description or Catalogue

See PRONI reference D/3030 for catalogue of the papers. The catalogue is available for consultation in PRONI's Public Search Room.

See also for an introduction to the collection.


Accrual Policy
Accrual Method
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The papers were donated to the National Trust, for permanent preservation in PRONI.

Associated Collection
Added by PRONI | Last updated on: 25 August 2018