Tenth Presidential Friday is dedicated to John Tyler, the US's tenth president. Among his nicknames are "His Accidency," as he rose to the presidency after William Harrison's death. He served the country from 1841 to 1845.
As a Whig, the inaugural address he issued seemed to fit the Whig platform nicely. However, Tyler was initially a Democrat who turned to the Whig party mostly out of opposition to Jackson and van Buren. When Tyler vetoed a National Bank on the grounds of states' rights, the Whig political leaders expelled Tyler from their party. Every member of the cabinet aside from Secretary of State Webster resigned. Later in his presidency, upon vetoing a tariff bill, a committee led by John Quincy Adams brought up impeachment charges on the grounds of misuse of veto power, though these charges did not succeed.
Though on the domestic front, the opposition of the Whig party led to little development, Tyler formed treaties with both Britain and China during his presidency. He also dedicated the last two years of his presidency to annexing Texas. He laid the groundwork and Congress passed the resolution in his last days as President. The annexing was carried out by Tyler's successor, President Polk.
Though he sought re-election, neither the Whig party nor the Democratic party could identify with his hybrid policies, and he ended up a one-term President. In later years, in 1861, John Tyler sided with the Confederacy in the Civil War and became a member of the Confederate House of Representatives.
He is held in generally low esteem, or often viewed as an obscure President. However, his ascension to the Presidency following William Harrison's death set a precedent for succession should a President die in office. This eventually became codified in the 25th amendment.
Sources: Potus.com, White House.gov, Wikipedia