The suspected presence of a German mine had for some time caused anxiety, and it was therefore decided to send out a party to find and destroy the shaft in the German trenches. Lieutenant the Hon. W. A. D. Parnell, Sergeant Lyon, and eleven men volunteered for the expedition. As soon as the moon had gone down the party started off over the parapet, and advanced cautiously through the long grass which covered the ground between the two lines. They had to cross a stream which was composed of water pumped from the enemy's trenches, but fortunately found a shallow place through which they were able to wade. On arrival at the German trenches they cut the wire, and silently one by one dropped down in the trench, but not a soul was to be seen. They moved slowly forward until they reached the communication trench, where they left two men to look out, and then went down the communication trench, but after going on for about forty yards they heard voices. Their mission was not to alarm the enemy, but to find out if there was an entrance in the German trench to a shaft of any description; so having satisfied themselves that none existed, they returned by the same route they had come, and reported all they had seen to Lieut.-Colonel Jeffreys. On the night of the 17th two patrols were sent out to explore the enemy's front trench. Lieutenant the Hon. W. Parnell, accompanied by Sergeant Lyon, again started off with eight men. No rifles were carried, but each man was armed with a bludgeon about eighteen inches long, with an iron ring round the head. Two men carried six bombs each. A second party was sent off by the 2nd Battalion Coldstream, and left at the same time. On arrival in the German trench, which they again reached without opposition, the Grenadiers went to the left and the Coldstream to the right. The party of Grenadiers advanced slowly down the German trench. They had not gone far before they observed a faint ray of light from a dug-out. Lieutenant Parnell halted the party, and directed Sergeant Lyon to go on ahead and see whether there was any sign of a sentry. Sergeant Lyon crept on, and saw that not only was there a sentry, but that on each side of the trench there was a small place hollowed out large enough to hold a man, and, what was more, there was a man in each hollow. Having located the exact position of these Germans, Sergeant Lyon returned, and reported what he had seen. The whole party then advanced, and Sergeant Lyon flung himself on the sentry, who made no attempt to alarm the others, and did not offer any resistance. The man was accordingly bound and gagged. One of the other Germans in the hollow managed to get out and fire off his rifle before he was bludgeoned. The other made a similar attempt, but was killed before he could manage to fire.