Having taken Horatio Hornblower’s career to levels of squadron command and international diplomacy, C.S. Forester’s Mr. Midshipman Hornblower and Lieutenant Hornblower go back to when he was just getting started.
Mr. Midshipman is a series of short stories dealing with incidents from the beginning of Hornblower’s career. It’s interesting (and occasionally amusing) to see a young, uncertain Hornblower who feels awkward at speaking in naval jargon and isn’t the commanding presence we’ve come to know. Despite which, this is probably the weakest entry in the series so far, as the dramas are small-scale and quickly dispensed with. Which is as it had to be, really — you can’t write a Hornblower story where he’s not driving the events to a large degree, and it’s unrealistic for a midshipman to be driving significant events — but still somewhat less satisfying than you’d hope.
Lieutenant, however, is entirely satisfying. Hornblower is still young, but far more experienced nevertheless, and he’s starting to display here the traits that make him the formidable leader he becomes — even if he’s not, technically speaking, in command. This is yet another excellent Hornblower book.
I will say, though, that having read these two books now, which are listed as the first and second in the editions I have (which lists them by chronological, rather than published, order), I think you could read the series in either order. These do work well as introductions to the Hornblower series, and going from Lieutenant Hornblower to Beat to Quarters wouldn’t be jarringly weird. But overall, the publication order that I’ve been following still seems like the best bet.