I am writing a paper, and I was wondering if a president has to be citizen, or can be a general. I thought that a president, like eisenhower, had to first resign being a general, and then could become president. What is the answer to this question? Thanks!
Theoretically yes. There is no explicit law banning a sitting general from being elected to the Presidency of the United States. However, there are several laws regulations ethical guidelines etc., that make it nearly impossible for a sitting general to be elected as president. Basically a general would be forced to win election without campaigning for himself. As a general you could be court marshaled for speaking ill of elected officials. Currently DoD Directive 1344.10 Dated February 19 2008 would govern the general/admiral/any other member of the armed forces behavior.
Additionally, as spelled out in the directive above, the general would have to receive permission from: the Secretary of Defense, Secretary of the respective branch, and the secretary of Homeland Security. Then, they would have to overcome various legal challenges to their candidacy questioning each of the points of the DoD directive.