 In 1866 Lewenhaupt was appointed head of the Ministry for Foreign Affairs' political department and in 1870 of its trade and consular department.Lewenhaupt was appointed State Secretary for Foreign Affairs in 1873.In his position as envoy 1876-84 and acting consul general in Washington, D.C., he was accepted by the Spanish and United States governments as arbitrator in the dispute that arose between them because of the uprising in Cuba.