The following take from "Beneath Flanders Fields: The Tunnellers War 1914-1918"
(Most paragraph breaks are mine.)
"We decided to try and enter the enemy tunnels. Cutting away the soft wet clay and removing debris in frantic working an entrance was made in about 20 minutes. We put on our Proto sets - oxygen apparatus for breathing in mine rescue and gassy areas. taking four sappers and my sergeant, all armed with revolvers, knuckle-knives and grenades we crawled into the German tunnel and started up the gallery. Now, Proto sets are alright for working in an ordinary civilian mine gallery, but crawling along or bent over in a war time tunnel of 4 x 3 feet is not so good - and fighting in a Proto set is an art to be learned.
Although the German tunnels were a bit larger than our own, the size was still very small. So, in the dark with our torches we crept down the German tunnel towards the blown in face. We found no bodies there. We returned the way we had come and went further up to find out more of their system. Going towards the German front line for 40 or 50 yards we came to a fork, with another tunnel leading at an angle towards our lines, so we knew than that this must lead to the workings we had blown in at point A. We went down the tunnel and found the face blown in and the bodies, or parts of, two Germans. We also heard out party clearing an entrance and this was done in a few minutes.
As we had gained so much enemy tunnel I decided to try to have a go and destroy as much as we could without too much loss to our own men. I instructed the party to prepare two heavy charges, and for an NCO and sapper to carry them and follow us some distance behind. My party of six then set off back up the German tunnel knowing that we should most likely run into trouble as the enemy would certainly send in a rescue or fighting party after two explosions.
With myself leading and my sergeant behind me followed by four sappers, all in single file, we had just started down their main tunnel when we heard and then saw torches coming in the distance towards us. Their heavy boots made such a noise and they were shouting or talking very loud. The atmosphere in the tunnel was still thick with dust or gas from the explosions. Not knowing how many of them there were I decided it would be best if we came back and waited just past the fork junction to see what would happen.
We waited for a few minutes with our torches out and all quiet. Then suddenly there appeared through the semi-darkness with their torches blazing in front of them, seven Germans, first a sort of NCO armed with a revolver, then five armed with revolvers and grenades, and the last was a junior officer also armed with a revolver. For a moment I thought they were coming down the tunnel straight at us, but no, they decided to go down the other tunnel. They still were making a lot of noise considering the job they were on. My thoughts went to my own two men who were coming up the tunnel with the two charges - they would run right into the German party. We waited until the Germans had gone a few yards past the fork so as to get up the room to get up behind them, then we kept in our stockinged feet silently up behind the enemy in single file.
Ever so quietly we gained on them and in a few seconds I was only about four yards behind the last man, the officer, and then all of a sudden they saw the torches of my other two men coming towards them. Thinking they were their own men from the face they shouted in German, and they all stopped. Then, as no reply came they jabbered a bit amongst themselves for a second or two, then the NCO in front fired a shot down the tunnel. Back came a shot from my boys right on the second. So now, being only a few yards behind the enemy I put on my torch and so did my men behind me. The Germans were taken completely by surprise, absolutely trapped, with their enemy in front and behind them. The man in front of me, who was their officer, turned round half facing me and with my torch shining in his face, he had his revolver pointed at me in a second; but he sort of hesitated, no doubt struck dumb by the grotesque sight of a hooded body coming at him.
It must have been an awful sight for them to see us in a Proto set in that dim semi-darkness.
I shot him before he recovered from his shock. At the same time keeping my body down to the floor level to allow my sergeant in a crouching position to shoot over me, and the others behind to fire over us. This was something we had practiced in training.
The German party never had a chance, their NCO was shot in the leg and my sergeant kicked his revolver out of his hand, but he rolled over, grabbed his gun again and was starting shooting, so the sergeant shot him again. The fighting did not last more than two or three minutes, then one of the Germans shouted 'Kamerad' and we soon disarmed the three enemy left standing. But the Germans fought well and hard, and if they had not been subject to such bad luck in getting trapped, they might have won the fight and killed the lot of us.
The casualties were Germans: one officer, one NCO, two men dead; three captured alive, one very badly wounded; Canadians: three men wounded, one badly. The last two sappers of my own party in the rear never fired a shot but both got hit themselves. We knew the enemy would be sending another larger rescue and fighting party so we laid our first explosive charge on a time fuse 50 yards up the main tunnel from the fork, dropped one near the fork itself, and ran as fast as we were able with our Proto sets still on to our own tunnel entrance.
We had just reached the entrance when both charges went off and knocked us all flat on our faces with the enemy tunnel caving in at the back of us, catching the last sapper of our party and trapping him in falling debris and timbers; we pulled him out but one of his legs was broken.
Getting back into our own tunnels we laid an explosive charge. This completed the blowing of the enemy tunnels and we knew we had stopped all the German works in that direction for a few weeks to come."
Lieutenant John Westacott
2nd Canadian TC
Westacott later had another more deadly encounter at Mount Sorrel, when he and a complete section of his men were trapped underground during a surprise German surface attack which captured the British front line trenches. Unknowing, the Canadian tunnellers emerged unconcernedly from a shaft at the end of their shift, to be spotted by the Germans.
Diving back down the shaft and sounding alarm bells as they went, they blew in several other entrances to the tunnel system, and waited. The Germans piled down after them and one of the most grisly battles of the war took place.
Fighting with grenades, pistols, rifles, and hand-to-hand with knives, bayonets and even razor sharp spades in the tiny galleries, the encounter was horrific. Westacott himself was almost to lose an arm, whilst sixty out of eighty of his shift were killed or wounded. The struggle lasted almost twenty-four hours - and the stopped just as suddenly as it had begun. When the tunnellers plucked up the energy and courage to tentatively peep out of a shaft again, they discovered that the Canadian infantry had recaptured the trench.