James Buchanan document signed as President, undated but 1859 given content. Buchanan here authorizes a ''Full Power to Robert M. McLane, Esq. to negotiate a Treaty with the Republic of Mexico...[signed] James Buchanan''. McLane was sent to Mexico in 1859 to negotiate a treaty with the new President of Mexico, Benito Juarez, following the end of Mexican-American War. The resulting McLane-Ocampo Treaty gave extraordinary concessions to the United States in return for funding Juarez's liberal government to fight the conservative faction in Mexico. Analysts of the treaty opined that it would essentially make Mexico a protectorate of the United States. The treaty, however, was rejected by the U.S. in 1860 amidst the swirling of pre-Civil War division. Single page on bifolium measures 8'' x 10''. Mild soiling, split starting along horizontal fold. Integral blank leaf has large closed tear. Overall in very good condition.