On May 9, 1846, President James K Polk began to prepare a war message to Congress, justifying hostilities on the grounds of Mexican refusal to pay U.S. claims and refusal to negotiate with John Slidell over the dispute of Texas’s border: ending either at the Nueces River (Mexican claim) or the Rio Grande River (American claim).
That evening he received word that Mexican troops had crossed the Rio Grande on April 25 and attacked Gen. Zachary Taylor’s troops, killing or injuring 16 of them. In his quickly revised war message—delivered to Congress on May 11—Polk claimed that Mexico had “invaded our territory and shed American blood on American soil.”
Congress overwhelmingly approved a declaration of war on May 13, but the United States entered the war divided. Democrats, especially those in the Southwest, strongly favoured the conflict. Most Whigs viewed Polk’s motives as conscienceless land grabbing. Indeed, from the outset, Whigs in both the Senate and the House challenged the veracity of Polk’s assertion that the initial conflict between U.S. and Mexican forces had taken place in U.S. territory.
Further, legislators were at odds over whether Polk had the right to unilaterally declare that a state of war existed. Principally at issue was where the encounter had actually taken place and the willingness of Americans to acknowledge the Mexican contention that the Nueces River formed the border between the two countries. Active Whig opposition not only to the legitimacy of Polk’s claim but also to the war itself continued well into the conflict. In December 1846 Polk accused his Whig doubters of treason. In January 1847 the by-then Whig-controlled House voted 85 to 81 to censure Polk for having “unnecessarily and unconstitutionally” initiated war with Mexico.
Among the most-aggressive challenges to the legitimacy of Polk’s justifaction of war was that offered by future president Abraham Lincoln, then a first-term member of the House of Representatives from Illinois. In December 1847 Lincoln introduced eight “Spot Resolutions,” which placed the analysis of Polk’s claim in a carefully delineated historical context that sought to
obtain a full knowledge of all the facts which go to establish whether the particular spot of soil on which the blood of our citizens was so shed was, or was not, our own soil at that time.
Ultimately, the House did not act on Lincoln’s resolutions, and Polk remained steadfast in his claim that the conflict was a just war.
Abolitionists saw the war as an attempt by the slave states to extend slavery and enhance their power with the creation of additional slave states out of the soon-to-be-acquired Mexican lands. One abolitionist who agreed with that interpretation was author Henry David Thoreau, who was incarcerated in July 1846 when he refused to pay six years’ worth of back poll taxes because he felt the U.S. government’s prosecution of the war with Mexico was immoral. Although he spent only a single night in jail (his aunt, against his wishes, paid the taxes, thus securing his release), Thoreau documented his opposition to the government’s actions in his famous book-length essay Civil Disobedience (1849), insisting that if an injustice of government is
of such a nature that it requires you to be the agent of injustice to another, then, I say, break the law. Let your life be a counter friction to stop the machine.
When war broke out, former Mexican president and general Antonio López de Santa Anna (the vanquisher of the Texan forces at the Alamo in 1836) contacted Polk. The U.S. president arranged for a ship to take Santa Anna from his exile in Cuba to Mexico for the purpose of working for peace. Instead of acting for peace, however, on his return, Santa Anna took charge of the Mexican forces.
Following its original plan for the war, the United States sent its army from the Rio Grande, under Taylor, to invade the heart of Mexico while a second force, under Col. Stephen Kearny, was to occupy New Mexico and California. Kearny’s campaign into New Mexico and California encountered little resistance, and the residents of both provinces appeared to accept U.S. occupation with a minimum of resentment. Meanwhile, Taylor’s army fought several battles south of the Rio Grande, captured the important city of Monterrey, and defeated a major Mexican force at the Battle of Buena Vista in February 1847.
So let’s talk about Taylor’s two manuevers here. The first being his capture of the Mexican city of Monterrey, occurred on September 25, 1846, and after a week of maneuvering, skirmishing, brutal assaults, and deadly house-to-house fighting. General Zachary Taylor moved his 6,640 many army into position north of the city on September 19, scouted its approaches, and captured the road leading to Saltillo the next day. A Mexican army of 5,000 men under General Pedro Ampudia waited behind fortifications, effectively cut-off from reinforcements.
Taylor planned a two-pronged assault for September 21, with General William J. Worth’s Division to attack from the west and southwest while the regulars under the temporary command of John Garland demonstrated against Monterrey’s eastern defenses. Worth’s assault carried the important positions atop Federation Hill, then moved on to capture redoubts on Independence Hill, as well giving U.S. troops command of the heights overlooking the city.
Fighting east of the town bogged down, and Garland’s command required the assistance of General William O. Butler’s reserves to finally carry the Mexican positions at La Tenería, Fort Diablo, and Purísima Bridge. With American forces east and west, Ampudia drew in his lines in the following day, fortifying the houses around the central plaza, the cathedral, and the imposing citadel, Black Fort.
Fighting resumed on September 23 with the Americans making impressive gains before being ordered to fall back at sundown. The following day, U.S. artillery began a systematic bombardment of the Mexican positions, leading to Ampudia’s request for a parlay. The two generals agreed on an eight-week armistice and the Mexican forces marched away with their weapons on September 25, giving the city over to the Americans. The Mexicans suffered an equal number of losses.
After the Battle of Monterrey in September 1846, most of Major General Zachary Taylor’s Army of Occupation was sent to the gulf coast to become the bulk of Winfield Scott’s expedition against Mexico City. Taylor felt that President James K. Polk was attempting to deprive him of any further military success which would aid in his campaign for the presidency. Taylor decided to ignore orders to stay in Monterrey; he marched deeper into Mexico and seized Saltillo. Taylor also diverted the Center Division, under John E. Wool, from its expedition in Chihuahua to join him in Saltillo. With Wool’s division, the U.S. force totaled about 4,500 soldiers, most of them volunteer units fighting for the first time.
In the summer of 1846, Antonio López de Santa Anna returned from exile and quickly seized power. When Monterrey had fallen, Santa Anna raised an army in San Luis Potosi numbering almost 25,000. When a letter from General Scott to Taylor telling of the transfer of the bulk of Taylor’s army to the Gulf fell into Mexican hands, Santa Anna quickly marched north to try and knock Taylor out of Mexico while U.S. forces were being withdrawn (Chidsey 1968, 112-113).
Taylor learned that Santa Anna was marching north and so he moved about nineteen miles south of Saltillo to Agua Nueva. Taylor sent out Major Ben McCulloch, of the Texas Rangers, to scout out the Mexican Army. McCulloch found Santa Anna 60 miles (100 km) to the south, informing Taylor on February 21. Taylor withdrew to a mountain pass at Buena Vista twelve miles north of Agua Nueva. General Wool was charged with laying out the defenses. Later that day Santa Anna arrived at Agua Nueva with 12,000 men, his force diminished because of desertion and exhaustion during the long trek from San Luis Potosi. Santa Anna perceived the U.S. withdrawal to Buena Vista as a retreat and demanded a surrender. Taylor’s aide, William Wallace Smith Bliss, eloquently replied that the U.S forces declined the surrender. Taylor, worried about the safety of his supplies, rode to Saltillo that night to ensure the protection of his rear.
On the morning of February 23, General Pedro de Ampudia attacked the U.S. left flank guarded by the second Indiana from Joseph Lane’s Indiana Brigade. The volunteers were supported by a battery of artillery but were steadily driven back along with a second line of Illinois volunteers. Wool sent a messenger to General Lane to hold the line at all costs. The Illinois volunteers managed to conduct a fighting withdrawal under the pressure of the Mexican attack.
General Taylor returned to the field and made his presence known to his men; he was escorted by the Mississippi Rifles under Colonel Jefferson Davis. The Mississippians hit the flank of Ampudia’s attacking column and Davis was wounded in the foot. Meanwhile Wool rallied the broken regiments using the walls of the hacienda at Buena Vista as a defensive position supported by a battery under Thomas W. Sherman and two regiments of dragoons. The third Indiana was brought to the support of Davis, and the two regiments formed an inverted V. The Mexicans attacked this new line. The Hoosiers and Mississippians held their fire so long that the confused attackers paused briefly and were then hit by a wave of gunfire. About 2,000 Mexicans were pinned down. A young Mexican lieutenant attempted to trick the U.S. into a cease fire by saying that Santa Anna wished to meet with the U.S. commander. Taylor and Wool saw through the ploy, but it did buy the trapped Mexicans enough time to escape.
Santa Anna renewed an attack on the main U.S. position led by General Francisco Pérez with artillery support. An artillery battery under Braxton Bragg unlimbered with orders to maintain his position at all costs. Taylor rode over to Captain Bragg, and after a brief conversation in which Bragg replied he was using single shot, Taylor ordered “double-shot your guns and give them hell, Bragg” (Chidsey 1968, 117). Later this order, although misquoted as “give them a little more grape Captain Bragg,” would be used as a campaign slogan which carried Taylor into the White House. Pérez’s attack was repulsed as heavy rain fell over the field. During the night Santa Anna declared victory and withdrew to Agua Nueva, after receiving a letter from Mexico City declaring that Santa Anna was needed to quell a Political Coup
The Americans racked up nearly 750 casualties, including 267 killed. Mexican casualties are unknown, but are presumed to have been far higher since they had remained on the offensive throughout the battle. The Mexican Army did leave behind over 500 dead soldiers on the battlefield.
The battle was the last major battle in northern Mexico. It was Taylor’s greatest battle of the war and also his last; he returned to the U.S. to pursue his political career. His success at Buena Vista and his legendary command to Captain Bragg helped him win election as President of the United States in 1848. Santa Anna suffered great losses and withdrew to the south when on the verge of victory. His withdrawal was spurred on by Political Dissent in Mexico City. He was later forced to defend Mexico City against an army under Winfield Scott.
Numerous heroes emerged from the battle, but in the end it was a long and bloody engagement that had yielded little in terms of strategic gain for either army. Both retained relatively the same positions that they had occupied prior to the conflict.