A map with all the trenches which have been put in the inventory up to October 2004 (left).
One of the many wartime aerial photographs used for the inventory. Trenches (green) and wire entanglement (red) are marked (right).

In 2001 a first attempt was made to make an overview of the archaeological World War One heritage in the villages of Houthulst, Klerken, Jonkershove and Merkem. This region is not a part of the Ypres Salient, but the German frontline follows the border from Merkem along the Yser River and the Ieperlee Canal (this stream runs from the Yser to Ypres). Klerken, Jonkershove and Houthulst were part of the German backlines. The forest of Houthulst was used as the headquarters of the Germans for both the Yser Front and the Ypres Salient. The region clearly was an important area during the Great War.