US History Trivia: Who was the first President to be known as "His Accidency"?

43 men have been President of the United States.  Depressingly, eight of those men have died in office, meaning that 18.6% of all men to serve as President have died while doing so.  Of course, when the President dies, the Vice President assumes the office.  While this is something that most of us consider to be relatively standard now, it was not always the case.  So, off of Pocket Trivia: US History - Who was the first President to be known as "His Accidency"?  Was it Andrew Johnson, Lyndon Johnson, Chester Arthur or John Tyler?

The answer to this one is John Tyler, the 10th President of the United States and the first Vice President to succeed a President after the death of the previous office holder.  Tyler served as William Henry Harrison's VP and took over office when Harrison died, barely a month into his Presidency.  Since this was the first time such succession had ever taken place, there were many questions about Tyler's advancement.  Was Tyler simply an Acting President who's role was to fulfill the duties of the office, or was he, indeed, the President?  Some in Congress felt that it was the former; Tyler, however, firmly believed that he was the President - he immediately had himself sworn in and presided over his first cabinet meeting shortly thereafter.

Eventually, Congress was impressed enough with his actions to pass a resolution that declared Tyler the 10th President of the United States, and this ultimately became accepted practice.  That being said, Tyler was still referred to by his detractors as the "Accidental President," or "His Accidency," making Tyler the first (though not the last) to bear this name.