John Tyler was the 10th President of the United States, serving from April 4, 1841, to March 4, 1845. He was the first vice president to assume the presidency following the death of a sitting president, William Henry Harrison. A member of the Whig Party, Tyler's presidency was marked by significant political conflict, particularly with his own party, as he often vetoed legislation that aligned with Whig principles, leading to his expulsion from the party. His administration is noted for the annexation of Texas, which would later contribute to the Mexican-American War.