[2] Following consultations between the Engineer-in-Chief of the BEF, Brigadier George Fowke, and the mining specialist John Norton-Griffiths, the War Office formally approved the tunnelling company scheme on 19 February 1915.

[3] To make the tunnels safer and quicker to deploy, the British Army enlisted experienced coal miners, many outside their nominal recruitment policy.

[2] The success of the first tunnelling companies formed under Norton-Griffiths' command led to mining being made a separate branch of the Engineer-in-Chief's office under Major-General S.R.

[1] In the Somme sector of the Western Front, local but very fierce underground fighting had taken place in the winter of 1914 and spring of 1915 at La Boisselle, Fricourt, Bois Français and Carnoy.

[4] The tunnelling companies were to make two major contributions to the Allied preparations for the Battle of the Somme (1 July – 18 November 1916) by placing 19 large and small mines beneath the German positions along the front line and by preparing a series of shallow Russian saps from the British front line into no man's land, which would be opened at zero hour and allow the infantry to attack the German positions from a comparatively short distance.

[5][9] After its formation, the company was employed in the Hebuterne-Beaumont-Hamel sector of the battlefield, where it helped prepare the opening of the battle on 1 July 1916 and continued operations throughout the fight.

[1] In the north of the battlefield, the unit dug a large mine, code named H3, at Hawthorn Ridge Redoubt[1] and prepared twelve Russian saps[10] facing Serre.

In the early hours of 1 July, the 1st Battalion Lancashire Fusiliers would use this tunnel to move up into the "Sunken Lane", the starting position for their attack on Beaumont-Hamel.

[11] The two other tunnels were Russian saps, dug to within 30 yards (27 m) of the German front line, ready to be opened at 2:00 a.m. on 1 July, as emplacements for batteries of Stokes mortars.

[13] The tunnellers under the command of Captain Rex Trower[8] dug a gallery for about 1,000 yards (910 m) from the British lines about 57 feet (17 m) underground beneath the German position on the crest of the ridge.

The ground all round was white with the débris of chalk as if it had been snowing and a gigantic crater, over fifty yards in diameter and some sixty feet deep gaped like an open wound in the side of the hill.Many Germans were entombed in a large dugout, all four entrances of which were blocked, but they were rescued later in the day.

The 2nd Royal Fusiliers, crossing no man's land to occupy the crater, came under heavy German rifle and machine-gun fire from either flank and the rear lip.

Between October 1915 and April 1917 an estimated 150 French, British and German charges were fired in the 7 kilometres (4.3 mi)-long Vimy sector of the Western Front.

During the pursuit after the Second Battle of Bapaume, 42nd (EL) Divisional RE had one field company on front-line work, with Captain Dean's section of 252nd Tunnelling Co attached to search dugouts and roads for booby-traps and mines, clear broken bridges wit explosives, and it also reconnoitred village wells that had been damaged by the retreating Germans.