He flew bombing missions over Vietnam (and probably Laos and Cambodia, too). The A-4 was/is not a 'fighter'; it's an 'attack' aircraft, a small, versatile, fast bomber.
He didn't "fight."
He bombed. 23 missions. 23 medals. One per hour in flight, approximately.
If he ever got into air-to-air combat, for example, it's not in any of his biographical material (and it would be if he had, for instance, shot down a MIG), and he has no air combat medals among the dozens of medals of which he was the recipient.
Mainly, that is, he slaughtered civilians, bombed roads and hiways, bridges and trains, and agricultural features like dikes and canals. And attacked power stations, and other civilian targets.
Which was what he was doing when they shot his murderous, war-criminal ass down.
And which was why they treated him pretty badly.
He deserved it!
He did behave pretty well as a prisoner, however.