Shortly before war against Mexico was declared by Congress (May 1846), General Zachary Taylor engaged Mexican forces in two battles near Brownsville, at Palo Alto and Resaca de la Palma. Taylor was not quick to follow up on these actions; the general claimed he was waiting for supplies, but many in Washington began to question his drive and his competence. American forces were fortunate that the Mexican army did not stage a major attack in the late spring of 1846; U.S. soldiers had been badly weakened by tropical diseases, sanitation problems and a lack of supplies.
It was not until September, 1846 that Taylor engaged the Mexicans at Monterrey. Although the Americans prevailed, a large number of the Mexican forces were allowed to withdraw uncontested. President Polk reacted angrily; he used the event to justify assigning a portion of Taylorís army to Winfield Scott, who prepared a plan for landing forces at Vera Cruz and marching on the Mexican capital.
While preparations for that campaign were under way, Taylor defeated a large Mexican force under Santa Anna at the battle of Buena Vista (February 1847). In this encounter, the Americans were outnumbered about three to one, but victory was assured in part by a dramatic cavalry charge under Colonel Jefferson Davis. This triumph, widely reported in the Whig press, made Taylor a national hero and would lead him to the presidency in 1848.