US Grant was a briiliant General and a terrible President. Rutherford B. Hayes was a former general and a poor President.
Looking at our wartime Presidents
War of 1812 James Madison had no military experience (WON)
Civil war Abraham Lincoln Limited military service (During the Black Hawk War, Abraham Lincoln of New Salem, Illinois served three enlistments. Each enrollment lasted for approximately 30 days.)
(HIS SIDE WON)
World War One Woodrow Wilson had no military experience (WON)
World War Two FDR had no military experience (WON)
Korea Truman and Eisenhauer both had military experience (DRAW)
Vietnam JFK and Nixon had military experience (LOST)
DESERT STORM Bush the Elder had military experience (WON )
Kosovo Bill Clinton had no military experience (WON)
IRAQ/AFGANISTAN/IRAN GW Bush Military experience ? Outcome (I will leave that to you)
IN MY VIEW ONLY EISENHAUER HAD THE KIND OF MILITARY EXPERIENCE THAT IS RELEVANT TO BEING COMMANDER-IN-CHIEF. NIXON AS A NAVY LIEUTENANT COMMANDER MIGHT HAVE SOME RELAVANT INSIGHT . TRUMAN AS AN ARTILLARY CAPTAIN IN WORLD WAR ONE MIGHT HAVE SOME CLAIM.