Conversation so far:
What branch of military did Ed McMahon serve in?
Ed McMahon was a Marine Corps flight instructor in F4U Corsairs for two years.
Did Ed McMahon serve in any wars?
As an officer in the reserves, Ed McMahon was recalled to active duty during the Korean War.
Was Ed McMahon wonded in service?

Question: What rank did he achieve by the end of his service?
Self-contained rewrite: What rank did Ed McMahon achieve by the end of his military service?