"William Henry Harrison's death marked the first time in American history that presidential power abruptly transferred from one man to another. It is a testament to the American system that without precedent or clarity in the Constitution, power transferred so seamlessly and swiftly through a seminal historic moment of ambiguity. This particular transfer of power was made all the more remarkable by the extraordinary set of circumstances that led to the annexation of Texas in 1844 and precipitated war with Mexico. The war, which was fought by Tyler's successor, James K. Polk, failed to win popular support from a population that supported admission of Texas, but preferred not to fight."
January 1, 1970
https://en.wikiquote.org/wiki/William_Henry_Harrison