A Concise History of the U.S.-Mexican War


The State of Texas

"Congress doth consent that the...Republic of Texas may be erected into a new state, to be called the State of Texas, with a republican form of government, to be adopted by the people of said Republic."

- Joint Resolution of Congress
   March 4, 1845

2. Countdown to War

In 1835 the Anglo-American settlers of Texas, aided by private citizens from the United States and a handful of Tejano compatriots, rebelled against the government of Mexico. On March 2, 1836 they declared Texas an independent republic. When Mexican President Antonio Lopez de Santa Anna led an army into Texas to put down the rebellion, he was defeated and captured by General Sam Houston at the Battle of San Jacinto, April 21, 1836. While a prisoner, Santa Anna ordered his troops to leave Texas and signed the secret Treaty of Velasco, which recognized both Texian independence and the Rio Grande as the boundary of Texas. Although the Mexican Congress repudiated the treaty, the Republic of Texas maintained its independence. Moreover, an act of the Texian Congress declared the Rio Grande to be the fledgling republic's southwestern boundary, despite the fact that as a Mexican province the border of Texas had been the Rio Nueces, some 160 miles further north. In 1842 the Texians went so far as to send a military expedition, which was unsuccessful, to occupy Santa Fé, New Mexico, a city which lay within the boundary claimed by Texas.

For nearly ten years the Republic of Texas was an independent country, recognized by the United States, France, Great Britain, and Belgium. Mexico, on the other hand, refused to accept the loss of Texas, considering it to be Mexican territory under the temporary rule of a rebel government. Consequently, when the United States formally offered terms of annexation to Texas in 1845 (shortly before James K. Polk was sworn in as President), Mexico recalled her ambassador, charging that the annexation of Texas was the same as an act of war.

In an effort to prevent Texas being annexed by the United State, Mexico belatedly offered to recognize the independence of the Republic of Texas in a "preliminary to a treaty" promoted by certain individuals in both Mexico and its former province. Because it was conditional upon Texas remaining independent of all countries (including the United States), this move failed to gain support in Texas.

On July 4, 1845 a Texas convention accepted the U.S. offer, a decision which was overwhelmingly affirmed by the voters of Texas in the fall. On December 29, 1845, Texas was formally admitted to the Union.

After Mexican leaders threatened to invade Texas, for purpose of reconquering the lost province, the governments of both the Republic of Texas and the United States mutually agreed that the U.S. would station troops on Texas soil as soon as the offer of annexation was accepted. By the end of August 1845, Brigadier General Zachary Taylor (nicknamed "Old Rough and Ready") and his men were in place at Corpus Christi, with more troops arriving almost daily to add to the strength of Taylor's "Army of Occupation."

During the fall of 1845 Mexico agreed to receive a U.S. diplomat for the purpose of negotiating a peaceful solution to the two countries' differences. In addition to the question of whether or not Texas was free to join the American union, there was a matter of numerous unpaid claims against the Mexican government by private U.S. citizens. Exercising the discretion granted him by the Secretary of War, General Taylor held his troops at Corpus Christi, so as not to antagonize Mexico by moving deeper into the so-called "Nueces Strip," a thinly-populated territory lying between the Rio Nueces on the north and the Rio Grande on the south.

By the time John Slidell, the American envoy appointed by President Polk, arrived in Mexico, the government was in political turmoil and refused to receive him. While Slidell was in Mexico, attempting in vain to carry out his mission, the moderate government of President Herrera was overthrown by the militant Manuel Paredes. After Paredes became President of Mexico relations between the two countries went from bad to worse.

On January 13, 1846, realizing that negotiations were no longer possible, President Polk instructed General Taylor, through Secretary of War Marcy, to take up a defensive position on the north bank of the Rio Grande. In March 1846 Taylor and his men left Corpus Christi. Upon arrival in the Lower Rio Grande Valley they set up a supply depot at Point Isabel and constructed an earthen fieldwork opposite Matamoros. Not surprisingly, the Mexican military commander in Matamoros, Francisco Mejia, responded by making threats and demanding that the Americans withdraw.

Zachary Taylor, being a dutiful old soldier, refused to budge, telling General Mejia that he'd been sent there by the President of the United States and until Polk directed him to leave, he intended to stay. Taylor also informed the Mexicans that in his opinion he had not taken any hostile action, although the Mexican government claimed that the mere presence of the troops was a hostile act. Taylor declared that if a war began, the responsibility for it would lie with whomever fired the first shot, something he and his troops did not intend to do.

As a precautionary measure General Taylor asked the U.S. Navy (its considerable contributions to the U.S. war effort often overlooked) to blockade the mouth of the Rio Grande. He considered it a fair response to the state of war which the Mexicans insisted already existed. In a letter to General Pedro Ampudia, who superseded Mejia, Taylor adamantly maintained it was a nothing more than a defensive measure.

During this same uneasy period, the Mexicans encouraged U.S. soldiers to desert by clandestinely distributing circular letters in the American camp. These letters were openly addressed to the foreign-born soldiers of the U.S. army, appealing, in the case of those from other Roman Catholic countries (particularly Ireland) to come to the aid of a fellow Catholic country (Mexico). Generous offers of land may have convinced both Catholic and Protestants to swim the river. General Taylor's response to what soon became a worrisome problem was to order his pickets to shoot on sight any U.S. soldier seen swimming to the south bank of the Rio Grande. After at least two men were dealt with in this manner, sinking beneath the muddy waters of the river, desertions dramatically declined.

On April 10, 1846 Colonel Trueman Cross, a veteran officer, failed to return from horseback riding near the American fort. Several days later the skeletal remains of Cross' body were discovered not far from the American encampment. Because his death appeared to have been caused by civilians, rather than by Mexican soldiers, General Taylor did not consider the Colonel's murder a warlike act of the Mexican government.

Throughout April 1846 tension mounted along the border. During this period the Mexican government first sent Pedro Ampudia to head the Mexican forces at Matamoros. Ampudia was soon superseded by Mariano Arista. The number of Mexican troops at Matamoros also greatly increased during that anxious month and before April ended, there were probably in excess of 6,000 soldados encamped across the river from the American earthworks now named "Fort Texas." This was more than twice the number Taylor commanded.

On April 24, 1846, Mariano Arista addressed a letter to Zachary Taylor in which he made it clear that it was only a matter of time before the forces under his command would cross over the Rio Grande and attack Taylor's "Army of Occupation." During the month it had taken for the Mexican government to assemble a large force at Matamoros to oppose them, the Americans had built substantial fortifications at both Point Isabel and the camp opposite Matamoros. When the time came to respond, Taylor and his men were ready.



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