[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.

[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.

[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.

[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.

The New Zealand Tunnelling Company arrived at Plymouth on 3 February 1916 and was deployed to the Western Front in northern France.

[1] 175th Tunnelling Company was formed at Terdeghem in April 1915, and moved soon after into the Railway Wood-Hooge-Armagh Wood area of the Ypres Salient.

[8] In the grounds of the Château de Hooge was a German strongpoint which was proving particularly troublesome to the British forces defending the area.

It is a significant fact that all their recent attacks round Ypres have been directed on hill tops and have rested content on the same, without trying really hard to advance down the slopes towards us.

This occurred during a time of relative quiet on the British part of the Western Front, when few major assaults were made.

[11] The mine fired by 175th Tunnelling Company at Hooge on 19 July 1915 was only the second British offensive underground attack in the Ypres Salient.

Having handed over its share of the work at Messines, 175th Tunnelling Company moved to Vimy, an area of busy underground activity for much of the war.

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.

[19] 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.

[19] After September 1916, when the Royal Engineers had completed their network of defensive galleries along most of the front line, offensive mining largely ceased[17] although activities continued until 1917.

The British gallery network beneath Vimy Ridge eventually grew to a length of 12 kilometres (7.5 mi).