Zachary Taylor

Zachary Taylor was an American military leader and politician who served as the 12th President of the United States from 1849 until his death. His presidency is chiefly notable for a crisis of whether or not New Mexico and California would become slave states, which ended in the Compromise of 1850 (after his death). Despite being a slaveowner himself, he told Southerners agitating for secession in no uncertain terms that he would crush them if they tried. He died shortly afterward, leading to rumors that he was poisoned. He was the last president to own slaves while in office. He was also the first president with no prior political experience, which didn't matter to him as he believed in figurehead chief executive.

Context
Zachary Taylor had fought in many wars, being a captain in the War of 1812 and later fought in the and  but he achieved national fame after defeating the Mexicans at Buena Vista. Unfortunately for him, Democratic president Polk replaced him with Winfield Scott, who would make the successful push toward Mexico City. This angered Taylor enough that he would publicly join the opposition Whig party, becoming their nominee for president in 1848, owing to his status as a war hero. He made Representative Millard Fillmore of New York his Vice President, in order to convince Northerners that it was okay to vote for a man who owned over one freaking hundred slaves. Though his campaign traded more on his personality than his polices, he won anyways since the Democrats were divided over the dominant issue of the time, slavery, specifically whether the states of California and New Mexico (formed from the Mexican Cession) would make slavery legal or not. Their actual nominee, wanted them to choose for themselves under the "popular sovereignty" concept, while former president Martin Van Buren ran a third party campaign opposing the expansion of slavery into western states.

Sectional Crisis
His brief presidency was almost entirely dominated by the question of how to treat these new territories. Southerners wanted them to be slave states, and hoped as a fellow slaveowner he would be sympathetic to their concerns. They misjudged him — he felt that slavery was impractical, owing to the geographic conditions of the west (i.e., not good for plantations), so as far as he was concerned the Union was being jeopardized over nothing. This lead him to support Northerners who just didn't want slavery to expand, though he obviously did not share their hatred of the 'peculiar institution'.

Death
On the somewhat ironic date of July 4, 1850, Zachary Taylor became severely ill after eating iced milk and raw cherries. Due to the suddenness of the death and his opposition to admitting California and New Mexico as slave states, it led to a theory that he was poisoned. If true, that would make him, not Abraham Lincoln, the first president to be assassinated. However, a group of coroners who exhumed his body in 1991 determined that he didn't die of poison, but they were unable to conclude what had really killed him as his body had decomposed too much by that point. The most common theories are cholera and acute gastroenteritis, and he wasn't helped by his doctors giving him dangerous "medicine" like calomel that was nonetheless accepted at the time.

Legacy
He is widely regarded as the best Whig president, but this is not a significant achievement when the competition is an old man who died of pneumonia just one month into his presidency, his Vice President and a flaming racist future Confederate who was hated by his own Whig party, and a guy whose most infamous deed was passing the Fugitive Slave Act. More importantly, he would be the first of many presidents who would try and fail to solve the question of whether to expand slavery into the territories. His successor Millard Fillmore passed the Compromise of 1850, which added California as a free state but left the question of slavery open in Utah and New Mexico, agitating Southerners who would become a minority in the Senate but also irritating Northerners with the aforementioned Fugitive Slave Act, which forced ordinary citizens to help catch escaped slaves. The next president after that, Franklin Pierce, made things worse by signing the Kansas-Nebraska Act, which undid the previous compromises and left open the possibility of slavery to expand to Kansas and Nebraska, leading to bloodshed in those territories. Then James Buchanan took over, but seemingly didn't even care about keeping the nation together and pursue peace, as he led the country to become even more divided. To add to this, his failure to properly deal with the Sectional Crisis and his incompetence led to a chain of events that ultimately led to the American Civil War, although Abraham Lincoln did manage to keep the union together by defeating the South in order to ban slavery and declaring freedom to the slaves in the South.