WWI Wytschaete, Belgium Trench Maps Office Use & Field Use Comparison

[The photos below show trench maps of Wytschaete, Belgium. The map on the left is for Field Use and the one on the right is the Office Copy. Both maps have railway additions made to them. The office copy map on the right also shows rail lines that were dismantled and water pipe lines. The key to that map is the second photo.]