McLane–Ocampo Treaty

The treaty granted perpetual transit, military and other extraterritorial rights to the United States and its citizens on Mexican soil and was controversial in both Mexico and the United States. For Mexico, it was seen as a betrayal of the country by ceding sovereignty to the United States, which had already defeated Mexico and annexed vast amounts of its territory in the Mexican–American War a decade before, but it promised the financially strapped liberal government the means to continue the war against conservatives.

Newspapers in Europe and in the United States expressed astonishment at the magnitude of the concessions that had been made and opined that the treaty would turn Mexico into a protectorate of the United States. Ultimately, the U.S. Senate rejected ratification of the treaty in 1860. If it had been ratified, it would have given major control over Mexican territory that was seen as a crucial transit point from the Caribbean to the Pacific Ocean.

Background

During the Reform War, the Conservatives sought financial support from Spain. The Mon-Almonte Treaty was signed on 26 September 1859 by Juan N. Almonte, Mexican conservative and Alejandro Mon, representative of Queen Isabella II of Spain, in Mexico.

The McLane-Ocampo Treaty was negotiated by Robert M. McLane, U.S. Ambassador to Mexico, and Melchor Ocampo, Mexican Minister of Foreign Affairs. It was signed in the port of Veracruz in Mexico on December 14, 1859. It would have sold the perpetual right of transit to the Isthmus of Tehuantepec to the U.S. for $4 million through the Mexican ports of Tehuantepec in the south, to Coatzacoalcos in the Gulf of Mexico free of any charge or duty, for military and commercial effects and troops. It even required Mexican troops to assist in the enforcement of the rights permanently granted to the U.S.

Additionally, it granted perpetual rights of passage through two strings of Mexican land: one that would run through the state of Sonora from the port of Guaymas on the Gulf of California, to Nogales, on the border with Arizona; and another one from the western port of Mazatlán, in the state of Sinaloa, going through Monterrey all the way through Matamoros, Tamaulipas, south of present-day Brownsville, Texas, on the Gulf of Mexico. Mexico was also compelled to build storage facilities on either side of the Tehuantepec isthmus.

Of the $4 million for the total cost of those benefits, the U.S. would pay immediately $2 million to the Mexican government, and the rest would stay in U.S. hands in provision for payments to U.S. citizens suing the Mexican government for damages to their rights.

Although U.S. President James Buchanan strongly favored the arrangement, and Mexican President Benito Juárez badly needed the money to finance the war that he was waging against the Conservative Party, the treaty was never ratified by the U.S. Senate because of the imminent civil war in the U.S., whose northern free states were concerned that its provisions, particularly the free transit of military effects and troops through the isthmus, would benefit the soon-to-become Confederate States if there was an open civil war.

The U.S. hoped to build a railroad or canal across the isthmus to speed transport of mail and trade goods between the eastern and western coasts. Roads there and in Nicaragua and Panama already carried considerable traffic.