Look at this picture. When one thinks of the invasion of Belgium we think a wide open plains. Easy terrain for both cavalry and infantry. No hills. Some rivers. But looking at the picture of the 30 or so kilometers between the German border and the fortress at Liège you can see that this is pretty rough country. This terrain had to be covered before anybody started attacking any forts in Liège. In addition, and more importantly, the railroads leading from the homeland through Liège had to be open and free to move along with large amounts of supplies. Supplying the German army was a function of railroads cars. Therefore, we would expect that the Great General Staff of the German army would ensure that their plan included clearing these railroads. But that part of the plan proved to be too tough of a nut to crack. So the Germans kind of ignored it and hoped for the best. This alone should be reason to run out and purchase the book.
In this rough terrain along the railroads were four tunnels that the railroads ran through. If the tunnels were not there the Germans would not have any choice but to build a bypass which could take months. So the Germans in the original Handstreich plan sent cavalry squadrons to secure the tunnels. Yes that’s right. The only plan was to assume that there would be no enemy resistance and send a few horsemen galloping many kilometers to secure this absolutely crucial point.
The Belgians were not stupid. They planned on dynamiting these tunnels prophylactically. While all four tunnels were rigged with explosives, they had serious problems with the age of those explosives and their vitality. Only one tunnel was permanently blocked through the use of these explosives. This picture shows the Trois-Ponts Tunnel.The plan was to create an obstacle in its middle. Six of the eight charges detonated caused an obstruction such that on August 11 the Germans started constructing a bypass track. They finished on August 30. Meanwhile, trains stopped on one side of the tunnel, and their cargo transshipped. German accounts said that on August 11 the line was cleared up to the tunnel of Trois-Ponts but with a break of forty-two meters in the middle it would take months to reopen. In consequence, the Germans then opted for a 1.75-kilometer bypass to span the River Salm, building a 120-meter long and twelve-meter high wooden bridge. That work lasted until August 28.
After that tunnel repair was entrusted to a private German company, Grün und Bilinger, which started work on August 30 and cleared the passage on one track by November 26. In early 1915, the Germans decided to rebuild the tunnel for two tracks while maintaining traffic on a single track. That work ended in December 1915.