27. THE MEXICAN WAR. Owing to its close association with the slavery contro versy the Mexican War has been the subject of almost endless dispute. Many people be lieved at the time, and many others still believe, that it was forced on by a Democratic admin istration in order to secure more territory in the Southwest for the extension of slavery. It would be difficult either to prove or to disprove this view conclusively. The immediate cause of the war was the annexation of Texas. The Democratic platform of 1844 favored annexa tion, but at the same time it was equally explicit in asserting the American claim to Oregon, a territory which could not by any possibility be opened to slavery. To the party leaders this connection of the two questions may have been only a shrewd bit ofpolitics, but President Polk's determination to fight for 54° 40' showed that it meant much more than that to him. The success of the ticket also indicated that it meant more to the American people. The constant cry of a slaveholders' conspiracy would not blind them to the advantages of acquiring so much valuable territory. At the time of the annexation, Texas (q.v.) had been an independ ent republic for nine years, recognized as such by the leading nations of the world. Although the Mexican government had made no serious attempt during that interval to reassert its rights, it now notified the United States that an nexation would be regarded as a cases belli. The passage of the joint resolution of 1 March 1845 was, in consequence, followed by the re call of the Mexican Minister at Washington and the formal suspension of diplomatic rela tions.
In addition to the Texas question there was a long-standing controversy in regard to the claims of Amencan citizens against the Mexican government. During the numerous revolutions which had occurred since Mexico gained her independence Americans had often suffered im prisonment and loss of property. A claims con vention of 1839 provided for a board of com missioners to pass upon these cases. There was some delay, however, in making the payments, and a second convention was concluded in 1843, in which Mexico agreed to pay all claims within five years in quarterly instalments. A few payments were made, but in 1845 they had again fallen very much in arrears.
In October 1845 President Polk informed the Mexican Secretary of State that he wished to settle the questions in dispute amicably, and that he was ready to send an envoy with full power to act. The secretary made an evasive
reply in regard to the subjects to be discussed, but expressed a willingness to receive our repre sentative. The President at once commissioned John Slidell, of Louisiana, as envoy, and he set out for his new post in November. The war fever was so strong in Mexico when Slidell ar rived that President Herrera was forced to refuse him an audience. A revolution, which occurred a few days later, resulted in bringing General Paredes, the head of the war party, into power. Being again refused recognition, Slidell returned to the United States in March 1846.
If annexation and the spoliation claims had been the only questions involved, the war might still have been averted. But a controversy arose in regard to the western boundary of Texas. The Congress of Texas in 1836 asserted that the boundaries of the republic extended to the Rio Grande. Historically the claim to the territory between the Nueces and the Rio Grande was of doubtful legality, but owing to internal difficul ties the Mexican government had taken no steps to assert its authority. Texas was admitted into the Union with "the territory properly in cluded within and rightfully belonging') to it, but subject to the adjustment by the United States government of all questions of boundary that might arise with other governments. If the Mexican authorities had received Slidell this question might properly have come up for dis cussion. Their refusal left but one course open to the President, namely, to treat the Nueces-Rio Grande tract as American territory. The rev enue laws were extended to it, and Corpus Christi, a town west of the Nueces, was made a port of entry. The Mexican authorities re sented this intrusion, and a large force of men under General Ampudia were stationed on the south bank of the Rio Grande, preparatory to an invasion of the disputed territory. To op pose him, Gen. Zachary Taylor with about 2,000 men was ordered to advance to the north bank of the river, opposite Matamoros. On 12 April Ampudia warned Taylor to withdraw beyond the Nueces within 24 hours or take the consequences. The warning being disregarded, General Arista, Ampudia's successor, sent no tice on the 24th that hostilities were com menced. On the same day a considerable force of Mexicans crossed the river a few miles above Matamoros and defeated a detachment of United States dragoons.