What was John Martin thinking when he enlisted?

The following is what my main character, John Ulysses Martin, was thinking at a certain time and place.

I've had this burning desire ever since I was child in Clarksville, TN to become a military officer. At the University of Virginia, where I graduated in 1861, I sold all my books and furniture, and bought a good horse with saddle. Readied myself for the unknown of becoming an officer in General Lee's fine army. But the Army turned me down because of a bad leg, and I was left in distress about what to do next.

Then, I had this dream about Thermopylae, and I was transported back to the battle of Thermopylae in 480 BC. In my dream I met a young maiden driving errant lambs on a mountain path above.  Her name was Arete, and she had intelligent blue eyes and long brown hair. Her voice sounded like the wind sighing through the tops of the tall trees.  

At the approach of the Persian troops under Xerxes, I told her to leave because her life was in danger.