were apart, even during lulls along the rest of the Somme front. On the night of , a German sapper inadvertently broke into French mine gallery, which he found to have been charged with explosives; a group of volunteers took 45 nerve-racking minutes to dismantle the charge and cut the firing cables. The French mine workings were taken over when the British moved into the Somme front. George Fowke moved the 174th and 183rd Tunnelling Companies into the area; at first the British did not have enough miners to take over the many French shafts; the problem was temporarily solved when the French agreed to leave their engineers at work for several weeks. On 24 July, 174th Tunnelling Company established headquarters at Bray, taking over some 66 shafts at Carnoy, Fricourt, Maricourt and La Boisselle. No man's land just south-west of La Boisselle was very narrow, at one point about wide, and had become pockmarked by many chalk craters. The British formed the 178th and 179th Tunnelling Companies in August, followed by the 185th and 252nd Tunnelling Companies in October. The 181st Tunnelling Company was also present on the Somme. Elaborate precautions were taken to preserve secrecy, since no continuous front line trench ran through the area opposite the west end of La Boisselle and the British front line. The site was defended by posts near the mine shafts. The underground war continued with offensive mining to destroy opposing strong points and defensive mining to destroy tunnels, which were long. Around La Boisselle, the Germans dug defensive transverse tunnels about long, parallel to the front line. On 19 November, the 179th Tunnelling Company commander, Captain Henry Hance, estimated that the Germans were away and ordered the mine chamber to be loaded with of explosives, which was completed by midnight on At the Germans blew the charge, filling the remaining British tunnels with carbon monoxide. The right and left tunnels collapsed and it was later found that the German explosion had detonated the British charge. From April 1915 to January 1916, were sprung around , some loaded with of explosives. Prelude 1916 At the start of the Battle of Albert (1–13 July), the name given by the British to the first two weeks of the Battle of the Somme, La Boisselle stood on the main axis of British attack. Royal Engineer tunnelling companies were to make two contributions to the Allied