Sunderland continued to take part in public life, and was active in communicating with the court of Hanover about the steps to be taken in view of the approaching death of the queen. He made the acquaintance of George I in 1706, but when the elector became king the office which he secured was the comparatively unimportant one of Lord Lieutenant of Ireland. In August 1715 he joined the cabinet as Lord Privy Seal, and after a visit to George I in Hanover he secured in April 1717 the position of Secretary of State for the Northern Department. This he retained until March 1718, when he became First Lord of the Treasury, holding also the post of Lord President of the Council. He was now effectively prime minister. Sunderland was especially interested in the proposed peerage bill, a measure designed to limit the number of members of the House of Lords, but this was defeated owing partly to the opposition of Sir Robert Walpole. He was still at the head of affairs when the South Sea Bubble burst and this led to his political ruin. He had taken some part in launching the scheme of 1720, but he had not profited financially by it; however, public opinion was roused against him and it was only through the efforts of Sir Robert Walpole that he was acquitted by the House of Commons, when the matter was investigated. In April 1721 he resigned his offices, but he retained his influence with George I until his death on 19 April 1722.
Sunderland inherited his father's passion for intrigue, while his manners were repelling, but he stands high among his associates for disinterestedness and had an alert and discerning mind. From his early years he had a great love of books, and he spent his leisure and his wealth in forming the library at Althorp, which in 1703 was described as " the finest in Europe." In 1749 part of it was removed to Blenheim Palace.
The earl's second wife having died in April 1716, after a career of considerable influence on the political life of her time, in 1717 he married an Irish lady of fortune, Judith Tichborne (d. 1749). By Lady Anne Churchill he had three sons and two daughters, from whom descended the later Dukes of Marlborough and Earls Spencer.
Text originally from 1911 Encyclopedia Britannica.