On February 26 1845, the U.S. Congress passed the Brown resolution, extending an offer of annexation to the Texas Republic. President John Tyler signed the resolution as his last act in office, and immediately dispatched a courier to Texas to present it to the government of Texas. On March 6, two days after the inauguration of James K. Polk, Mexico’s minister in Washington demanded his passports, thus severing diplomatic relations between his country and the United States.
Ominous as these developments seemed, Mexico’s president, José Joaquin Herrera, was anxious to avoid a conflict with Washington. And while he continued to look for ways to block annexation, he was equally determined to resist the demands of conservatives who insisted that only a war could redeem the nation’s honor.
Several months passed, but in the fall of 1845 a series of discussions between Herrera’s foreign minister, Manuel Peña y Peña, and U.S. consul John Black, the lone U.S. representative in Mexico, seemed to offer a way out of the impasse. In October, Black asked the Mexican minister if his government would agree to receive an envoy with the authority to "adjust all questions" between the two countries. Peña y Peña responded in the affirmative, stating that the Herrera regime wished "to settle the present dispute in a peaceful, reasonable and honorable manner." With these meetings, the groundwork for productive negotiations between the two countries appeared to have been laid. Believing that Mexico was now prepared to restore normal diplomatic relations, the Polk administration on November 10 appointed John Mason Slidell, a Louisiana attorney, as U.S. minister to Mexico.
In fact, Black and Peña y Peña had agreed to two very different things. The Herrera government had expressed a willingness to discuss only "the present dispute," i.e., the Texas question. Since this matter would first have to be resolved before normal diplomatic intercourse between the two countries could be restored, it assumed the Polk administration would send a commissioner empowered to settle Mexico’s grievances regarding the loss of its former province. Only then could Mexico receive a U.S. minister and resume regular diplomatic relations.
The Polk administration, on the other hand, regarded the annexation issue as settled, and declined even to give its diplomat the authority to discuss the issue. Since the Texas Republic had existed for almost a decade as a sovereign nation, and had now chosen to enter the Union of its own accord, Polk believed Mexico had no just cause for complaint.
Nor did Polk believe that Mexico had a valid claim to the stretch of land between the Rio Grande and the Nueces River, another bone of contention for Mexico. On this point he was prepared to be more conciliatory, however, regarding the boundary dispute as the principal obstacle to normal diplomatic relations between the United States and Mexico. To obtain the Herrera government’s recognition of the Rio Grande as the legitimate boundary of Texas, the president offered to assume payment of U.S. claims against the Mexican government totaling three-and-a-quarter million dollars.
Slidell’s mission would have been ambitious enough had it been limited to a satisfactory resolution of the Texas boundary dispute. But the Polk administration believed the time was ripe to pressure Mexico into making further concessions. Alarmed by reports of British interference in California, Polk instructed Slidell to warn Mexican leaders that the United States would take steps to prevent the cession of California to any European power. Should Mexico wish to sell the land, however, the United States was prepared to make several propositions. For the New Mexico territory, Polk authorized the U.S. envoy to offer the Herrera government $5 million. The administration was also willing to pay $20 million for a territorial cession that included the Pacific ports of San Francisco and Monterey.
Anxious to resolve its problems with Mexico as quickly as possible, the administration took the unusual step of sending Slidell on his diplomatic mission as a recess appointment, without waiting for Senate confirmation. On November 29, barely six weeks after Black and Peña y Peña had met to discuss the reopening of diplomatic channels, Slidell disembarked at Veracruz.
Slidell’s arrival caught the Herrera regime off-guard. Assuming that a U.S. envoy would not be named until the U.S. Congress convened in December, the Mexican government did not expect Slidell to arrive until early the following year. Peña y Peña had not yet had time to build support in the Mexican Congress and in the state legislatures for the regime’s controversial decision to open a dialogue with the United States.
Herrera’s conservative critics strongly condemned the regime’s apparent willingness to negotiate with the United States. Playing for time in hopes that the public furor might die down, Peña y Peña declined to accept Slidell’s credentials on the grounds that Mexico had agreed only to receive a commissioner empowered to settle existing grievances, not a minister plenipotentiary. He urged Slidell to write to Washington to obtain new credentials, a request the U.S. diplomat rejected.
By this time, however, conservative forces were now moving to supplant the Herrera regime. In a chain of events which had become all too familiar in Mexico, General Manuel Paredes y Arillaga, a conservative who had engineered the overthrow of Santa Anna one year earlier, issued a pronunciamiento against Herrera on December 15 and marched on the nation’s capital. On December 30, Herrera resigned and handed over the reins of government to Paredes.
Believing that a new government might be in a stronger position to negotiate with the United States, the U.S. diplomat withdrew to Jalapa, midway between the capital and the port city of Veracruz, to await further instructions from Washington. But the U.S. minister’s hopes for the success of his mission soon proved groundless. A man of strong anti-American sentiments, Paredes showed little interest in reaching an accord with the United States. In addition, Washington had already sent troops under General Zachary Taylor into the trans-Nueces and ordered its navy off the Mexican coast, warlike measures that made an accommodating posture on the part of the new regime politically untenable.
In mid-January 1846 the Polk administration learned of Paredes’ refusal to accept Slidell’s diplomatic credentials. Secretary of State Buchanan wrote to the U.S. envoy ordering him to sever diplomatic relations if Mexico did not abandon its position and recognize him as a representative of the United States. In March Slidell demanded his passports and prepared to return to the United States. With Slidell’s departure, all hope of a constructive dialogue between the two countries came to an end.
Arriving in Washington, Slidell briefed the president on May 8. The following day, Polk discussed the situation with members of his cabinet. Despite the absence of aggression on the part of Mexico, Polk now believed that its refusal to receive Slidell gave the United States "ample cause of war" and favored sending Congress a declaration to that effect. All cabinet members agreed except George Bancroft, who advised the president to wait until some act of provocation by Mexico.
In fact, the pretext for war which Bancroft sought had already occurred. At 6 p.m. that same evening, Polk received dispatches from General Taylor, notifying him that the Mexican army had crossed the Rio Grande, attacking a patrol of 63 dragoons on April 25. Sixteen Americans were killed and wounded in the exchange, and the rest captured. Taylor’s note read: "Hostilities may now be considered as commenced."
Sam W. Haynes