In this way a big gap was made in the Allied lines, through which the Germans advanced. But the Canadians quickly formed a flank on the left and stoutly engaged the enemy, with such success that they first slowed up and then brought to a halt the advance of the Germans. It was this prompt action and gallant resistance that probably saved the day. Whether the German high command had underestimated the probable effect of the gas and had arranged for only a limited objective past which the local commanders did not take the initiative to go, or whether the latter were unaware of the real weakness of the Canadian line is unknown. The fact remains that they did not press their advantage to the full. They had taken the Allied front line on a wide front, killed or captured thousands of men and taken sixty guns, and seemed to have a clear way through to Calais; but they were stopped by the pluck of a handful of Canadians. Reinforcements of men and guns were rushed up, and the immediate danger was over. It is a matter for surmise how long the Germans had been planning and preparing their use of gas. The idea may have been a pre-war one, but it is difficult to believe that a project deliberately planned for years would not have been developed so as to make it a sure winner--for it could easily have been that. If, for example, they had made the attack over a wider front with such strong gas clouds as are now used nothing could possibly have stood against them. Every living thing to a depth of fifteen miles or more could have been killed. On the other hand it is impossible to imagine the use of poison gas as having been decided on without better preparation having been made to meet retaliation, unless it was assumed either that the use of the gas would be decisive or that at any rate the war would be finished before the Allies could hit back with the same weapon. In any case the preparation must have been going on for months. All the production of material, organisation of personnel and so on takes a long time. This we realised ourselves later, for though the decision to retaliate with gas was made in May it was September before an attack could possibly be made. If we assume that a like interval of four months elapsed for the perfecting of the German arrangements it means that the decision to use gas was made about Christmas, 1914. The onus of urging the Kaiser’s advisers to adopt the use of poisonous gases had been laid at the door of Professor Nernst, professor of chemistry at the University of Berlin. Professor Nernst is a noted chemist, and even before the war was a notorious Pan-German and Anglophobe--one of the “professors” who carried too much weight in Germany and whose arrogance and shortsightedness helped to lure her to her downfall. Some time after the use of gas was started Professor Nernst was made a count by the Kaiser for his “notable services”--meaning presumably the use of gas in warfare.