Interesting well written book on a somewhat obscure and not that documented topic. The author manages to write a general portrait of the tunnellers war while at the same time doing a splendid job covering all the technical basis.
You'll find a bit of everything, the daily life of the sappers, the claustrophobia, the geology of Flanders and how technical problems were overcome, and the unfortunate and gruesome reality of war in the tunnels, or the frenetic digging from both sides as they both tried to gain an advantage and "lift" the other side with inordinate amounts of explosives planted below their trenches and strongholds. Specially interesting as well is the battlefield archaeology, the state of some galleries today that for some reason or other were drained, and that provide a glimpse into a surreal claustrophobic world complete with mattresses, bottles, spent cartridges, abandoned explosives where galleries had long collapsed.
If you're a mining engineer, a geologist, or have some interest in military engineer corps or in WW1 History in general, this book is absolutely mandatory. The way the authors manage to connect the many threads from many disciplines in a coherent narrative without burdening the reader with a dry speech while at the same time documenting solidly everything is superbly done. There's a good assortment of period photographs and the occasional diagrams illustrating shafts, galleries, geology, as well as contemporary photographs from recently found galleries, and their dangers. Many thanks to the authors for a splendid job.