Tunnelling Companies of The Royal Engineers - British Advantages

British Advantages

The British tunnellers had three advantages over their German counterparts, the Pioniere:

Firstly, the British used clay-kicking which was a virtually silent method of tunnelling. The Germans did not know of this technique, having not used it in their pre-war civil engineering, and thus used mattocks (a type of pick-axe) and other loud tools throughout the war. This made their tunnels more vulnerable to detection and attack.

Secondly, the use of clay-kicking made the British four times as fast at tunnel digging as their German counterparts.

Thirdly, British positions were most often located in low-lying areas, while German positions tended to be more elevated. Although this made the British more vulnerable to shelling, it also meant that British tunnellers had less of the soft quicksand-like 'Kemmel Sands' (known to the Germans as schwimmsands), an integral component of the geological make-up of the ridges around Ieper (Ypres), to penetrate. While the bottom blue clay layer was virtually flat, as was the Kemmel Sands that sat on top of it, there was a dry strata which varied above this which created the geographical contours. This varying dry strata increased pressure on the Kemmel Sands, which unable to egress water below them, made them wet and unstable. When punctured, the Kemmel Sands would often "spout" under pressure, both water and solid material. Difficult to dig through and keep the mining wooden structure stable, the Germans, assuming that the British had the same instability problem, dug few tunnels until 1916. The British found an engineering solution by creating a metal tube through the Kemmel Sands. Sunk either through its own weight or by the use of hydraulic jacks, once the blue clay layer was hit, the tunnelling could again resume under wooden supports.

The British used tube shafts from May 1915, a full year before the Germans, who when they did start to use metal and concrete tunnels, had lost the strategic advantage and were digging purely for defensive purposes.