While the American Whig Party technically won the presidential election of 1840, the death of William Harrison actually delivered the White House to their electoral opponents. Vice President John Tyler, a former governor of Virginia, was an apostate Democrat expelled from that party for opposing the policies of Andrew Jackson. The Whigs had added him to the 1840 ticket for sectional balance, and they were properly horrified when President Tyler reverted to his former political alignment, vetoing tariff and national-bank bills that the Whig Party considered cornerstones of its economic policy. Within a few years Tyler's entire Cabinet had resigned in disgust, the House of Representatives had considered (but rejected) impeachment proceedings, and editors were deriding the tenth president as “His Accidency.”
Tyler did not win his own term as president. In 1844 he endorsed Democrat James Polk for the presidency and persuaded Congress to approve a constitutionally-dubious joint resolution annexing Texas to the Union, which he signed in March 1845. He then retired from public life, having done what William Harrison almost certainly would not have done: deepened a sectional rift between North and South and created the pretext for war with Mexico, whose government still considered Texas a rogue province. In 1861, Tyler emerged from retirement to accept a seat in the Congress of the Confederate States of America, which his home state had just joined. He died before he could begin his term of service, though, and the War Department turned his confiscated Virginia estate into a refugee center and school for freedmen. In death, at least, Tyler could do something useful for the republic.
And so endeth this series for another year. There will be more presidential history next January, on Anti-Presidents' Day.