President at the time of the Mexican War. A career politician, he served in some capacity from 1823 until just before his death. A Democrat, he was nominated as their president for the Presidency in 1844 as a 'dark horse' candidate after deadlock and the Democratic Convention, where he had expected to be nominated only for the vice-presidency. Amongst his policies, were a determination to acquire California from Mexico, and to allow Texas into the union, two policies that contributed greatly to the outbreak of the Mexican War. He won the presidency because the Whig opposition was split, with the breakaway Liberty party taking enough votes off the Whigs to give him a 38,000 vote majority out of 2,638,000 votes.
Results of the Mexican War
He was the youngest president yet to serve, hard working, and closely involved with every element of his government. In 1846 he ordered troops to the Rio Grande, triggering war with Mexico. His relationship with General Winfield Scott, the commander of the US Army was fraught, as Scott was a dedicated Whig (and later stood for the Presidency himself). Thus Polk was unwilling to allow Scott too much glory from the war, and initially obstructed Scott's plans for an amphibious invasion of central Mexico, but was eventually forced to approve the plan. Once it succeeded, Scott was recalled to face spurious charges, but to Polk's embarrassment was received as a national hero, and awarded a congressional gold medal, which Polk had to present. Polk was never physically strong, and the demands of the presidency left him exhausted, and he died on 15 June 1849, only three months after leaving office.