[3] 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.

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

These companies each comprised 5 officers and 269 sappers; they were aided by additional infantrymen who were temporarily attached to the tunnellers as required, which almost doubled their numbers.

[3] 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.

[5] The formation of twelve new tunnelling companies, between July and October 1915, helped to bring more men into action in other parts of the Western Front.

[11] From spring 1916, the British had deployed five tunnelling companies along the Vimy Ridge, and during the first two months of their tenure in the area, 70 mines were fired, mostly by the Germans.

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

In the second half of 1916 the British constructed strong defensive underground positions, and from August 1916, the Royal Engineers developed a mining scheme to support a large-scale infantry attack on the Vimy Ridge proposed for autumn 1916, although this was subsequently postponed.

[12] After September 1916, when the Royal Engineers had completed their network of defensive galleries along most of the front line, offensive mining largely ceased[11] although activities continued until 1917.

[12] Prior to the Battle of Vimy Ridge (9–12 April 1917), the British tunnelling companies secretly laid a series of explosive charges under German positions in an effort to destroy surface fortifications before the assault.

The gallery had been pushed silently through the clay, avoiding the sandy and chalky layers of the Vimy Ridge, but by 9 April 1917 was still 21 metres (70 ft) short of its target.