The supreme court requested that Richard Nixon hands over the tapes that he had. If they had them, they could then see what he's done and how corrupt he was so he decided to resign before being impeached. That's why he's not on the short list of presidents who were almost impeached, the other two being Clinton and Jackson, both of whom were acquitted of charges.
if I were you I would do some research on them :)
John Quincy Adams is the answer
Many people think that a vigorous and strong president is incompatible with a republican form of government. Hamilton, however, does not agree. An energetic and forceful president is essential to good government. National defense, sound administration of the law, and the protection of property rights all depend upon the vitality of the Presidency. In addition, an energetic president best protects liberty when faction, anarchy, and the excessive ambitions of others threaten it.