The vice president with the highest enlisted military rank: Dan Quayle
With Tim Walz being selected to be the Democratic nominee for vice president, I was surprised to learn that he was a very senior enlisted soldier in the Minnesota National Guard (command sergeant major/master sergeant.)
This brings to mind the question - who is the vice president who had the highest enlisted rank? After looking at the Wikipedia entry for each vice president, I learned that there have been only three vice presidents who have served who have had enlisted rank:
Therefore, Dan Quayle is the vice president who held the highest enlisted rank in his military career.
(As an aside, the president who had the highest enlisted military rank is James Buchanan, who was a private.)