 He succeeded James Chamberlayne Pickett who had served as Plenipotentiary for signing a Treaty of Peace and Commerce with Ecuador.He presented his credentials on August 12, 1848 and served, during the presidency of Vicente Ramón Roca, until his mission was terminated on November 12, 1849 by a transmitted recall note.While in office, Polk reasserted the Monroe Doctrine which opposed European colonialism in the Americas.