Before the battle of Loos
Joffre's plan for the battle of Loos was clinical and simple. The strong enemy positions would be crushed by four days of continuous bombardment, with a final crescendo before the infantry initiated a telling breakthrough. For four days, beginning on 21st September 1915, the British artillery heavily bombarded the German lines all along the front from just north of the Canal d'Aire (often referred to as the La Bassée Canal) to Loos. The diary of a soldier in the Royal Artillery records, "It was like hundreds of railway trains going through the air" and on 24 September, "Thunderstorm last night and it was a whisper compared with the artillery fire." The next day, a Saturday, was the first day of the Battle of Loos (25 September – 18 October 1915). The Battalion headquarters moved up to the front line. It was very wet and muddy. Major Burrard wrote in the 9th Royal Welsh Fusiliers’ regimental diary that it was drizzling and what little breeze there was seemed unfavourable for the use of gas; "I began to think the attack would be postponed".
Successful use of gas relied on wind strong enough to carry it to the German lines but not so strong that it blew the gas cloud apart. In the garden of his chateau near Loos Haig asked his senior aide-de-camp to light a cigarette. He watched the smoke drift gently towards the German lines. It was barely adequate but this was the first battle in which the British anticipated using gas and without it the attack would have had to be on a much smaller-scale; he gave the order to launch the gas. The Germans had been using gas since April that year but the rudimentary British gas masks were so awkward that many men risked not using them when going into battle. The main attack was south of La Bassée Canal, and in places along that line the gas blew back on the allied troops causing over two thousand six hundred British casualties from the gas put up by their own side.
Sir John French arranged for subsidiary attacks to be made near Ypres and north of the La Bassée canal; the 9th Welsh Regiment were involved in the latter. The timing of the attacks both north and south of the canal and of the preceding barrages were synchronised along the entire front. At about 04.00 on the morning of the 25th the men of the 9th Welsh Regiment’s front line took up their positions ready to attack and C and D Companies moved up to No.6 and No.4 communication trenches in readiness to support them. At 05.30 orders were received that the gas attack would commence at 05.50. The men put on their smoke helmets.