First was Osprey Elite #77: British Colours & Standards 1747 - 1881 (1): Cavalry. As with other flag books, this has a point primarily for miniatures gamers who want to make realistic flags for their armies. It's mildly interesting historically, but otherwise I found the book boring.
Second was Osprey Men-at-Arms #43: Napoleon's German Allies (2): Nassau and Oldenburg. See, Napoleon was so powerful, at his height, that he could demand troops from many states in Europe to use in his conquests. Some, like the Poles, seemed happy with this. Others were less so. Again, this book was initially intended to help miniatures gamers who like the Napoleonic era to paint their figures accurately, so their units could look like individuals. Otherwise, this wasn't quite my cup of tea.
I have lots of these ebooks. Luckily, they are quick reads.