Here's a relatively new title which may be of interest to the blog readership. I refer to Vauban and the French Military Under Louis XIV: An Illustrated History of Fortifications and Strategies by Jean-Denis G.G. Lepage.
At first glance, for a paperback book weighing in at 286 pages, there isn't £32.93/$49.95 worth of content here. However, bearing in mind that this is a treatise lacking mass market economy of scale, and chock-full of excellent line drawings by the author, the reader can start to feel that his purchase has not been a wasteful expenditure.
While the book opens with a biographical sketch of Vauban himself and his role in the wars of Louis XIV, this is more of an in-depth survey of the French art of fortification under the Sun King's reign. The real meat of the text begins with the chapter on the art of fortification, followed by a comprehensive survey of France's frontier fortifications, rotating clockwise from the Pas de Calais and Flanders back around to Normandy. Each fortified place gets one or two pages of text outlining its history and Vauban's role in it, with an excellent line drawing of the fortress plans or a detailed sketch of some aspect of the fortress, city, gates and so on.
There are no photographs in the book, but given the care Mr. Lepage has lavished upon his illustrations, they won't really be missed. Recommended.