The Division continued holding this line until 20th September, when an attack was launched. This period was remarkable on account of three things. First, the mud, which reproduced conditions similar to, if not worse than, those at Courcelette. The ground throughout the whole front was so sodden with rain and churned up by shell-fire as to be impassable to troops in any numbers. The second feature was a consistently lavish use of the recently-introduced mustard gas, which caused numerous cases of slightly-gassed men, and a lesser number of men seriously gassed. The latter suffered indescribable agonies, and either ultimately died, or made an insufficient recovery ever to return to the ranks as whole men. The mustard gas shell proved itself to be a weapon that was liable to cause serious losses unless all measures for anti-gas defence were maintained at a high level of efficiency. It was, however, a persistent gas, and might cause casualties hours and even days after it had been used, so that the enemy could never employ it on an area which he intended to attack in the immediate future.
The third feature of this period was great activity in aerial bombing, which the Germans suddenly developed, and which they maintained in an increasing degree to within a few weeks of the armistice. Both bombing and long-range guns, which the enemy freely used in this front, were difficult to deal with, as shelter for the men could not be provided by means of dug-outs in the clay soil of Flanders. In consequence, both men and horses suffered a number of casualties from bombing, particularly in the camps and rest billets behind the line. On one occasion alone three bombs dropped in Siege Camp caused thirty-two casualties.
On 6th September the 5th Seaforth Highlanders attempted a raid on the enemy's posts in front of Pheasant Trench (see Map VII.), 3 officers and 100 other ranks being employed. The raiding party failed to reach the enemy's lines owing to the intensity of his rifle and machine-gun fire; but they obtained some valuable information, and caused the enemy serious losses by the energetic use of their rifles. They observed that Pheasant Trench was protected by an uncut belt of wire about fifteen yards in depth. They also found that in some parts Pheasant Trench was manned by dummies, and in others by men holding it in two ranks, the front rank using their rifles while the rear rank threw bombs. They took advantage of this close grouping on the part of the enemy by shooting twelve of them. During the advance a party of about twenty of the enemy left two advanced saps and made for the rear, but only four of them reached cover. The raiders could not regain our lines during daylight, and remained in shell-holes until dusk, when they returned, having lost 1 officer and 19 men killed, 2 officers and 18 men wounded, and 9 men missing.