First was Simon Scarrow's book, The Eagle's Conquest, second in a series about Roman soldiers under Emperor Claudius and his invasion of Britain. Pretty good, occasionally highly coincidental.
Second was Osprey New Vanguard #65: British Napoleonic Artillery 1793 – 1815 (2): Siege and Coastal Artillery, a pretty technical work that has some bearing on the nautical novels I've read in the past. Has a few interesting details.