WILLIAM BRANGHAM:

The tide has slowly been turning for transgender service members like Blake. Until last year, if a soldier, sailor, airman or Marine changed their gender identity, Pentagon policy was to give them a medical disqualification and discharge them from service.

This was policy, but it wasn't always strictly enforced. But last July, Secretary of Defense Ash Carter stopped these dismissals, and ordered the Pentagon to draft plans to allow transgender people to serve openly.

But that change came too late for some. As a man, Brynn Tannehill graduated with honors from the Naval Academy in 1997. She went on to serve as a Navy pilot for over a decade.