Examples of the influence of groundwater on British military mining in Flanders, 1914–1917
The success of military mining is inherently controlled by subsurface conditions. Military mining may be offensive (i.e. intended to breach enemy fortifications at the ground surface by explosive detonation), defensive (counter-mining to destroy enemy mine galleries) or passive (to provide troops with underground protection from bombardment). The geology of the British Sector of the Western Front in World War I varied from the Palaeogene–Neogene sediments of the Flanders Plain in Belgium to the late Cretaceous chalks of Picardy and Artois in northern France, all with intermittent Quaternary cover. In Flanders, British mining operations commenced in late 1914. Passive mining created shallow dugouts and isolated shelters, and offensive mines also tended to be shallow, rapidly dug, and of low engineering impact. By 1915, with the war above ground now largely in stalemate, the impetus for more extensive mining grew, leading to the high point of offensive mine warfare with detonations that initiated the Battle of Messines on 7 June 1917. Development of mine warfare required engineering innovations such as ‘tubbing’ to deal with major groundwater problems presented by variation in the permeability of the sediments, as can be illustrated by two examples from the battleground of Ypres (Ieper).