Conversation so far:
who was the strategic thinker and naval war college professor who developed the theory of sea power
Alfred Thayer Mahan was a United States naval officer and historian who developed the theory of Sea Power.
where was Alfred Thayer Mahan born
Alfred Thayer Mahan was born September 27, 1840.
when did Alfred Thayer Mahan die
Alfred Thayer Mahan died December 1, 1914.

Question: how many years did the historian serve in the military
Self-contained rewrite: how many years did Alfred Thayer Mahan serve in the military