The impending cholera epidemic felt like a game-changing storm at the end of the first volume of Two Years Ago, so it's disappointing when it actually hits and turns out to be a few people getting sick (except for one). What does cast a long shadow over the rest of Two Years Ago is the Crimean War. I think that this is the first Victorian novel I've read to actually deal with this in a substantive way; almost all the characters end up serving in the war in some way, shape, or form. (Though it's not as hard-hitting as something like Master Georgie, that's for sure.) Beyond that, there's just a lot of moralizing here, both from the narrator and Tom's father, but don't you worry: Tom soon learns that his keen scientific gaze can be used in the service of God and not just money (even he was functionally kinda doing this already). It turns out that atheistic cunning is best as tying itself up!

It's not quite so one-note as I'm making it sound, as there's a minister who learns from Tom that sitting around thinking about dogma isn't terrible useful; this novel led to the coining of the term "muscular Christianity" and it shows.