This was a false notion, picked out of a translation of Die Schlacht an der Yser und bei Ypern im Herbst 1914 (1918), which the official historians used...

fired along with the rest of the mines under Messines Ridge at the beginning of the Battle of Messines (7–14 June 1917). When the mines were detonated...

remained in German hands until the Battle of Messines in 1917, when two of the Mines in the Battle of Messines were detonated beneath Hill 60 and the Caterpillar...