|Books by Richard Whitten Barnes||
Very quickly, after Germany overran Belgium to attack France and rush to the important Atlantic ports, a 400+ mile front was established from Dunkirk on the coast to the Swiss border near Basel.
Eventually defensive trenches were established in that static war, and by its end in late 1918, the entire front was dug in with a continuous string of them.
The trenches varied widely depending on the terrain and conditions. For example: the marshy ground of Flanders required shallow trenches that were built up with sand bags. The chalky ground farther south near Lille allowed deep tunneling, and even extensive headquarter rooms.
Here's a typical trench design:
Think of it.
A chain of trenches like the system above laced from Chicago to Pittsburgh.
There remain remnants of the system (even the tunnels) to this day, 100 years later.