During the First Battle of Ypres in 1914 the British used the cover of a large wood south of the Ypres-Menin road for tending to their casualties. The wood was so named as it was providing a place of sanctuary to the wounded.
Both the German and the British Armies remained in and around the Sanctuary Wood until July 1917 when the British launched an offensive on the German lines for the Third Battle of Ypres.
In 1918 the Germans pushed the Allies back towards Ypres again and the two front lines were located to the west of Sanctuary Wood. This meant that the area was now east of and behind the German front line. The movement of front lines backwards and forwards over the same ground is typical of the WWI fighting during the four years of war in the Ypres Salient. This accounts for the absolute destruction of parts of the landscape over and over, and the reason why the bodies of so many thousands of soldiers from all sides have never been found.