On March 16, Yancey was formally appointed as the head of the diplomatic mission to England and France. Ambrose Dudley Mann and Pierre Adolphe Rost were also part of the mission; only Mann had any diplomatic experience. The delegation assembled in London at the end of April. Confederate Secretary of State Toombs' official instructions to Yancey were to convince Europe of the righteousness and legality of southern secession, the viability of the militarily strong Confederacy, the value of cotton and virtually duty-free trade, and the South's willingness to observe all treaty agreements in effect between Britain and the United States except for the portion of the Webster-Ashburton Treaty requiring aid in combating the African slave trade. Above all, Yancey was to strive for diplomatic recognition.