The British took over the Somme area from the French during July and August 1915. On 24 July, 174 Tunnelling Company moved to the Somme front and established headquarters at Bray, taking over some 66 shafts at Carnoy, Fricourt, Maricourt and La Boisselle. Prior to the takeover, La Boisselle had been the scene of much mining activity and underground fighting. No-mans-land just south west of La Boisselle was very narrow, at one point no more than about 50 yards (46 metres), and had become pockmarked by many chalk craters. The French and German forces were constantly mining and countermining, and the area became known as the Glory Hole.
Nothing changed when the British took over, the underground war continued with offensive mining designed to destroy enemy strong points, and defensive mining to destroy enemy tunnels. Depths of tunnels ranged from 30 feet (9 metres) down to the deepest at 120 feet (36 metres). Around La Boisselle the Germans had dug defensive transversal tunnels at a depth of about 80 feet (24 metres), parallel to the front line.
Tunnelling was a dangerous business, each side doing its best to detect and destroy enemy tunnels. On 4 February 1916, two officers and 16 men (See Appendix A) were killed, either being burnt or gassed when the Germans detonated a camouflet (a small explosive charge big enough to destroy enemy workings but not big enough to break the surface). Captain Richardson wanted to test the then very new listening device, the Geophone to see how accurate it was in pinpointing the direction from which sounds of enemy mining were coming. He had a three level mine system starting from Inch Street, La Boisselle, the deepest being just above the water level at around 100 feet (30 metres). Lieutenant Edward Lyall went to the deepest level and made deliberate noises, whilst Captain Richardson and Second Lieutenant Arthur Latham went into the middle level to see if they could use the Geophone to ascertain the direction from which Lieutenant Lyall’s noise was coming from. It was during this experiment that the Germans blew the large and unexpected camouflet that killed the 18 men.
Captain Thomas Charles Richardson (Left) and 2nd Lt Arthur Latham (Right)
The two officers killed in the camouflet at La Boisselle
For the 1 July 1916 attack two large mines were planned, one to the north of La Boisselle (Y Sap) and one to the south (Lochnagar). Both were ‘overcharged’ which means that more explosive was used than was necessary to just break the surface, so large rims were formed from the disturbed ground. The tunnel for the Y sap mine started in the British front line near where it crossed the Albert to Bapume road, but because of German underground defences it could not be dug in a straight line. About 500 yards (457 metres) were dug into no-mans-land before it turned right for about another 500 yards (457 metres). Some 40,000 lbs (18,144 kilograms) of ammonal (high explosive) was placed in the chamber beneath Y sap.
In addition to the two large mines, the Glory hole was also attacked with two smaller charges of 8,000 lbs (3,628 kilograms) each, designed to wreck German tunnels. Communication tunnels were also dug for use immediately after the first attack, but were little used. To try to ensure that the enemy did not find out about them, a high level of secrecy was maintained about their existence. So secret that Incredibly the attacking infantry did not know about them. An exception to this was the Russian sap from Kerriemuir Street which was eventually connected to Lochnagar Crater and the German front line. For some time this was the only means of crossing Sausage Valley. A battalion of the 19th Division and the 9th Chrshires passed through it, and it was used to evacuate the wounded.