Fascinating facts and figures from the Royal Engineers' Manual of Field Engineering 1911. A wealth of data about making defences, building bridges and blowing things up. Lots of useful information for anyone designing a wargame set in the late 19th or early 20th centuries. There's also a lot that can be transferred to medieval wargames and even RPGs.
As well as tables of data and extracts from the manual, there are reproductions of the original illustrations