Emerging as the dominant figure in government after 1717, following the Whig Split, he led Britain to success in a new Spanish War and suppressed a Jacobite Rising in 1719.

In 1701 Stanhope entered the House of Commons, but he continued his career as a soldier and was in Spain and Portugal during the earlier stages of the War of the Spanish Succession.

While Stanhope was in Lisbon recovering from an attack of fever his regiment was part of a Portuguese-commanded garrison which surrendered the town of Portalegre.

After a visit to England in which he took part in the impeachment of Henry Sacheverell, he returned to Spain for the campaign of 1710, with Allied victories at Almenar and Saragossa in July and August enabling Archduke Charles to enter Madrid in September.

[7] On the back of these triumphs, Stanhope was selected as the Whig candidate for the Westminster seat in the 1710 General Election, with his cousin Lt-General Sherington Davenport as proxy in his absence.

[9] The Tories won the General election in December by a landslide, by which time Stanhope was a prisoner in Spain but this theme was to form an important part of his future image.

Lack of support from the local population meant the Allies entered an almost deserted Madrid and were effectively isolated when Portuguese forces were prevented from crossing into Spain.

Stanhope's division was taken by surprise and forced to surrender by a French army led by Louis Joseph, Duke of Vendôme at Brihuega on 9 December 1710.

This caused Britain to withdraw from the war since a Spanish and Austrian union threatened the European balance of power, and was as unwelcome as a French one.

His activity was now shown in the conclusion of the Quadruple Alliance between Britain, France, Austria and the United Provinces in 1718, and in obtaining peace for Sweden, when threatened by Russia and Denmark.

The expedition was defeated at the Battle of Glen Shiel and in retaliation the British dispatched a force that briefly captured Vigo in October 1719.

Domestically, he promoted the Peerage Bill of 1719 to limit the membership of the House of Lords a controversial move as it was seen as an attack directed at his former Whig colleagues led by Walpole.

[17] Just after the collapse of the South Sea Bubble, for which he was partly responsible but from which he did not profit,[7] the earl was defending his government with customary vigour and panache in House of Lords on 4 February 1721 when he was taken ill with a violent headache.

[18] On the king's orders Stanhope was given a full military funeral through London on 17 February to Southwark, and he was afterwards privately buried at Chevening.

Basil Williams said Stanhope, "had no special bent for domestic politics.... His impetuosity and want of experience indeed led him into mistakes sometimes in dealing with internal questions."

Although Stanhope found little time for domesticity, it was a happy union, and the couple had seven children, including two sets of twins: His sister Mary, one of Queen Anne's six Maids of Honour, 1702–1707, married Charles, 1st Viscount Fane in 1707.