Everybody has heard by now that John McCain was shot down over North Vietnam, captured, and held as a Prisoner of War; it apparently, to some, is his main qualification to be President.
According to what looks like a reasonably well-sourced page on Wikipedia, a total of 3,032 aircraft were lost to hostile action during the Vietnam War (the actual total was considerably higher, as these numbers don't include Army rotary-wing aircraft), which means at least that many pilots were shot down (yes, some were shot down more than once, but they are way more than offset by the many aircraft that had two pilots).
The Air Force lost 1737, the Navy 530, the Marine Corps 463 and the Army lost 302 (fixed wing).
Of all those shot-down pilots, the experience apparently only made one uniquely qualified to be President.