To improve the British performance at taking mine craters and consolidating and holding captured positions, GHQ issued a set of printed instructions in May 1916. These emphasized that: ‘success will only result if there is also an absolute determination on the part of all ranks to get the work done promptly at all costs.’⁴²

When mines were blown, whether by the British or Germans, parties were to be rushed out immediately to seize the crater lip. If blown by the British in an attack on the German trenches, the object should be to seize and hold the whole crater, or a line in front of the crater. It was usually better to hold a line in front and to turn the crater or craters into strong points. When the craters were blown by the Germans, either as a result of an attack overland or fighting underground, troops were usually to seize and hold the near lip only. The British blew practice mines behind the lines to train their troops in capture and consolidation, two in May and one in June of 1916. The Inspector of Mines also made efforts to have these explosions filmed, probably because this was a means of observing and timing the fall of debris.⁴³

Given their performance at St Eloi, it is perhaps fortunate for the British that the mining attack on the Messines ridge did not take place in 1916. Haig’s Flanders attack was to fall victim to the requirements of coalition warfare, as he was obliged to cooperate with General Joffre in his proposed attack on the Somme. In contrast to the Flanders position, in which Haig saw real strategic possibilities, the Somme was chosen by Joffre solely because it formed a junction of the French and British forces and so was convenient for a joint attack. At the beginning of 1916, however, it seemed that the Flanders attack could still be the main British offensive of the summer, and throughout the first half of 1916 Haig kept the attack under preparation. The major German attack on the French at Verdun, which began on 21 February 1916, at first made it seem that the Flanders attack would take precedence over the Somme, as the French would not now be able to cooperate in the Somme attack. On 10 April British GHQ instructed Plumer to submit promptly his plan for capturing the Messines Ridge and its northern continuation, the Pilckem Ridge, with an attack to start on 15 July.⁴⁴ On 27 May he was ordered to press his preparations with all speed. The ferocious battle at Verdun had the effect of severely reducing the French contribution to the Somme offensive, but the British were obliged to mount their part of the attack regardless. By 4 June the Flanders attack was scaled back to include just the Messines element, because Rawlinson’s 4th Army was to be too far committed to the Somme offensive to attack in Flanders. Haig clung to the possibility that if the Somme attack was not a success, Gough’s Reserve Army could still be sent to Messines. However, after the decision to continue the Somme attack in early July despite the disastrous first day, the Messines attack was further reduced in scale and the date altered to 31 July. It was then postponed again, and by mid-August it was apparent that it would not take place in 1916.

Mining, however, came to dominate day-to-day trench warfare on the Western Front. In 1916 the British blew 750 mines and camouflets, while the Germans blew 696 against the British. The most active month was June and the most active sector was the front of the British First Army, which centred on the area Givenchy-lez-La Bassée, Hulluch and Loos.⁴⁵ The value of mines blown which were not part of a wider offensive plan was questionable given the labour which each required. On the Somme front, however, the British were attempting to use mining for the breakthrough offensive of 1916.