[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.

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.

[4] 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] It was then moved into the Ypres Salient, where it relieved 177th Tunnelling Company, which at that time was stationed in a wide area facing Wijtschate.

The logic behind the exact placing of the charges at Hollandscheschur Farm was to take out a small German salient (strongpoint Günther) that protruded into the British lines.

The main gallery of the Petit Bois mine was taken out by clay kicking over 500 metres (1,600 ft) and reached beyond the German lines when it was breached by enemy counter-mining.

After six days, the British tunnellers managed to rescue Sapper Bedson, a veteran of the Ypres Salient and of Gallipoli.

The shaft was sunk to 20 metres (66 ft), the heavy clay requiring much timber as the tunnel was driven forward to the German lines.

The main charge was eventually placed below Peckham Farm as planned and in time, some 400 metres (1,300 ft) from where the digging had started.