George Washington (David Morse) so quickly tired of the infighting among his Cabinet and vagaries of public opinion that he stepped down from the presidency after a single term.
Um, no, he didn't. Two-terms -- famously, served two-terms. Fourth-grade American History.
It's true that HBO's series has taken some liberties on the time-line of Adams' life (mostly in regard to his personal life, and the lives of his children), but they did manage to get that fact quite clear.