After 9th June, the hostile artillery slackened off considerably. High-velocity guns ceased to trouble the back areas, and the front trenches, except for occasional intense bursts, received little attention. On the 23rd the casualties in the entire Division for twenty-four hours had dropped to one man killed and two wounded. On 10th June a new form of gas attack was delivered on the Divisional front, known as a "gas beam" attack. Forty truck-loads of cylinders were run up to the most advanced point on the light railway, which lay in front of Bailleul and just behind the support line. Those cylinders were arranged so that they could all be opened simultaneously by an electrical device. This was a marked improvement on the old system, in which each cylinder required four men to carry it up to the front line, and then had to be left in position until a wind of the right velocity was blowing in the required direction, in danger of being burst by shell-fire and flooding our own trenches with gas. In the case of the "gas beam" the train was not moved up to the position of discharge until the wind was suitable, so that the gas could be released immediately on arrival, and was thus stored in the trench area for the shortest possible time. Prior to the discharge the front and support lines in the area liable to be affected by the gas were evacuated by their garrisons. The train carrying the cylinders was then moved into position without incident. A machine-gun bullet penetrated one of the cylinders, but the escape of gas was quickly stopped by the presence of mind of one of the gas personnel, who plugged the holes made in the cylinder with clay. The discharge then took place, and as far as could be seen the "gas beam" rolled slowly over to the German lines, the wind at the time having dropped to about four miles an hour. In the morning the Flying Corps observers reported that a broad belt of discoloured grass showed that the beam had travelled some 4000-5000 yards into the enemy's country towards Douai. What effect it had on the Germans is not known. No kind of alarms seem to have been given from the German front-line trenches. The German batteries in the area affected by the gas were, however, silent for several days. When the troops returned to the front and support lines after the discharge, they found numbers of rats, moles, and beetles dead at the bottom of the trenches, while the brass shell-cases hung up as gas-gongs were coated with a deposit of verdigris about the depth of a half-crown piece, evident signs that the gas was a fairly powerful mixture.