May I add my theory about this story being a hint of what would later be "The flight of the Heron? It's not as evident as the "Sir Isumbras" one, but there are lots of similar details, like despatches, h/c, hand holding, m/m vibes, swooning, tragic events... and Jacobites, of course!

"Some force (not my own will, sure) moved forward my hands, which met his in a grip as short as a lightning-flash, and as long as eternity. He gave me a look quite indescribable—of pity and forgiveness, and (I should not write it were I not sure) of affection."