Conversation so far:
When did James Stockdale become a prisoner of war?
On 9 September 1965, while flying from USS Oriskany on a mission over North Vietnam, Stockdale ejected from his Douglas A-4 Skyhawk.
What happened while he was a POW?
Stockdale was held as a prisoner of war in the Hoa Lo prison (the infamous "Hanoi Hilton") for the next seven and a half years.

Question: What happened during those 7.5 years?
Self-contained rewrite: What happened during the 7.5 years James Stockdale was a POW?