After serving in the Polish War, he was sent to London as secretary of legation. There, he married the Jacobite Sara Wright. In 1715, he was made minister plenipotentiary, and two years later was imprisoned for five months because of his participation in the plot to reinstate the House of Stuart. In 1723, he was appointed Councilor of State, and in 1738 Chancery President ( swedish, kanslipresident' ), that is both Prime Minister and Foreign Minister. While in this office, he founded the Hattparti or Hattar (‘Hat’ Party), which instigated the disastrous Russo-Swedish War (1741–1743), resulting in the loss of Kymmenegård. He was successively chancellor of the universities of Lund (1728) and Upsala (1739), was a patron of letters and art, and wrote several poems and the first Swedish comedy, Den svenska Sprätthöken (1740). His Letters . . . Relating to a Design to Raise a Rebellion on His Majesty's Dominions, to be Supported by a Force from Sweden, were published in French and English (1717).