The United States Constitution gives the President of the United States the military rank of Commander In Chief of the US Armed Forces. He has extreme control and command over the nation's military forces.
Considering that we have had two men who have held the rank of General (that is higher than Colonel) I would say two. They were Grant and Eisenhower.
Given that the highest rank possible in the US Military is Commander-in-Chief, and that the Commander-in-Chief is the President, they all held the highest rank possible. THE ABOVE answer I found here is incorrect. The Commander-in-Chief position is civilian, not military. The whole point of making the president C-in-C is to have civilian control of the military, unlike in other countries in the 18th century whose military did not answer to the government. The president is not a member of the military. I am told George Washington was the only six star general in history (before being president, of course), but I have not checked.
The US Presidents who were Civil War veterans who saw combat action were Grant, Hayes, Garfield and McKinley. Andrew Johnson has military rank as the military governor of Tennessee and Arthur was a supply officer in a non-combat position. Fillmore had a sort of honorary position in the home guard.
A great place to find a list of the Presidents of the United States of America is on Wikipedia. Another website that has the list of US presidents is 'PresidentUSA'.
50000000000000000000 how does that sound?
No six star rank ever existed in the US military.
Presidents do not appoint military officers. And if everyone you had in mind holds the rank of Colonel, then they'd all be of equal rank, although some may be in senior positions over others.
The President is the Commander in Chief. Highest Rank of the Military.
11th
US Presidents do not have to have served in the military in order to be elected.
In US, this is a "brevet" promotion
There are dozens of books that list all the presidents with their pictures. Or, you can google "US Presidents" and click on images.