The thing that I dislike about the story is the incongruent political structure. If he was dethroned they’d never let him near the military. Now that he’s a war hero, even if the citizens disliked the first prince the military men, having depended or followed him in battle would be enough to regain the crown.
It doesn’t make sense. I can’t think of an example where a dethroned prince got ahold of the military and it didn’t turn out poorly for the would be king.