I was reading Norman Gladden’s  book ‘YPRES 1917’ when i came across his account of his dealings with the Australian’s on Hill 60. Although the account is not specifically about tunneling, i found it fascinating of how one night on 5th June 1917 was spent assisting them.

“The next morning, immediately after I had drawn my fried bacon, I was unfortunate enough to be detailed to assist the Australian Tunneling Company, who had been carrying out mining operations towards the enemy positions for months on end, working day and night in six-hour shifts. This had been a war of wits. At times the Germans counter-mining had brought the enemy so close to the saps that galleries had been blown. There had been hand-to-hand fighting underground, and new galleries had had to be made, each side striving to get beneath the other. We had retained the ascendancy and a vast mine was now approaching completion. Immense quantities of ammonal had been buried and arrangements were already in hand for blowing the charge by electric ignition from behind the line. One job on this particular morning was to help with the construction of sandbagged barriers to tamp the charge and prevent blow-back along the galleries.

We were conducted by the free-and-easy Australian sergeant through a wonderful labyrinth of passages until we reached an opening into a sort of calm cul-de-sac outside the hill, where the air was fresh and the light seemed brilliant after being so long below ground. A high and considerable breastwork of sandbags zigzagged away to our right. The ground beyond rose to a low ridge in the middle distance. There was nothing the least ominous about the desolate scene: nothing moved and there was unusually little noise. We were pleased to be enjoying the sweet spring air even in such a setting. The working party spread out round a bend in the breastwork, forming tamping operation.
As it happened I was the end man in the chain and was standing at the corner of a traverse where the breastwork turned abruptly leftwards and quickly petered out in the waste. We worked with a will, for the task was a light one and the fresh air filled us with new vigour. We were pleased, too, by the novelty of the work and the friendly attitude of the N.C.O in charge. For once we quite forgot to grumble.
Indeed, there was poised just above the horizon the black speck of an observation balloon, though our sense of direction gave us no indication whether it was friend or foe. It was a characteristic of the Salient that one could never be certain.
A little later an enemy battery began firing and shells burst along the ridge, not much more than a hundred yards away. Another salvo passed over and crashed on to the hill behind us. In the shelter of the breastwork we felt secure and it certainly did not occur to us that we might be the real target. We seemed to harbour a trustful feeling that we should not have been brought out there had there been any special danger. Against all experience and reason, we continued to have childlike trust in the omniscience of those in command, and on this occasion everything had so clearly been well planned that no question had entered our minds. By this time the work had progressed so well that the sergeant decided to lengthen the chain. Three of us moved round the corner.
Suddenly the battery began firing again and there was something in the approaching scream that marked us as the target.
I cringed low as the first shell burst somewhere near the corner. Then we all began running like frightened rabbits back to the burrow, which now seemed so far away. As I turned the last bend a man a few yards ahead crashed to the ground. I recognized him as one of the youngsters of the recent draft and the very man who had just taken my place at the corner I had vacated. Aided by the man ahead, I attempted to lift our stricken comrade, but he was too stiff and heavy and we were now out there alone, some fifty yards or so from the sap entrance. A second salvo left the guns and terror took control of my senses. The next thing I knew I was leaning breathlessly against the timbers of the opening, panting and frightened. The rest of the party bunched undecidedly in the entrance. Shells were now lashing the breastwork but a little way from the opening which, however, was out of the line of fire. Here was safety; out there, but a few yards away, pain and sudden death. Our Australian N.C.O decided to report back to his headquarters for instructions.
Corporal Bell of our company, a quietly-spoken Londoner and commercial clerk in civil life, now appeared on the scene, elbowing his way through the indecisive crowd. On learning what had happened, which was not an easy matter for we were all talking at once, he demanded why we had not brought the casualty in. Our assertion that he was dead did not satisfy the corporal. “Come on, one of you men,” he said; “we must bring him in.” No one budged. I felt ashamed, but had no intention of going out there again unless I was directly ordered. Why shouldn’t someone else go?
Time seemed to stand still. The corporal lost patience: a last appeal and he started off alone. He doesn’t know what it was like, I thought. Then something stirred to override my fears. He couldn’t possibly be allowed to go alone. Against all reason I followed him. We raced along the breastwork. All was again quiet. We bent to raise the prostrate figure, but death had rendered the task of moving such a rigid corpse beyond our united strength, weakened no doubt by the stress and excitement of the moment. Shelling recommenced, scattering bags from the breastwork all around us. “Run!” shouted Corporal Bell, and with my remaining energies I ran as I never run before, as a tornado of bursts smashed down the breastworks under the shadow of which we had just been stooping. The enemy had really found the target and we two were lucky to survive.
Later on it was reported that the stretcher-bearers, who eventually retrieved the body, were of the opinion that the dead man had been immediately, for he had shrapnel in his brain and in his heart. Yet I knew that he had run a number of yards before he fell!

We were relieved to hear that the outside work had been abandoned and we completed our spell moving the accumulated bags along the galleries in trolleys. As the shift ended at 2 p.m. the Australians issued us with a tot of rum, so large compared with our normal issue that I dropped into deep sleep as soon as I reached the dug-out.”

Later on in the book Norman Gladden gives this explaination:

“The mine under Hill 60 mentioned in the text was the most northerly of the nineteen, but there was a second nearby on the other side of the Railway Cutting. Although by no means the largest of the mines, this was a considerable detonation, containing a charge of some 35,000 lb. of high explosive, mainly ammonal. The other mine just mentioned (of which the author was not at the time aware, although it was comparatively near) had a charge of 70,000 lb.”