Symbolism, Imagery, Allegory
Sometimes symbols show up time and again in books, and sometimes they make quick little appearances and then are gone. This is one of those.
In Chapter 10, Edmund and Hubert are walking down the street taking in the sights of London when all of a sudden they come across a guy beating a horse. We can think of this as a little shout-out to the sudden violence of war, but what pops out even more is Hubert's reaction:
But something about the bald man's grin of concentration as he belabored the horse stiffened Hubert. (10.25)
Just like that, we're given a heads-up that Hubert isn't going to take to war very well—violence tenses him up. Boy does he have some rude surprises coming his way… On the flipside, Edmund stays present enough to notice Hubert's reaction. He isn't consumed by this spectacle of violence, thereby subtly cluing us into the fact he will generally adapt to life during wartime better.