The afternoon of April 22 was drawing to a close, and a fresh breeze was blowing from the north-east, when the German Supreme Command decided that the moment had arrived for the perpetration of the crime that will brand the German Army with infamy until the end of time. Our line about Ypres ran, more or less as the first great German thrust for Calais had left it in November, in a wide semicircle about Ypres. The French were on our left on the east bank of the Yser Canal, along a line running eastward through Langemarck to the point where our line began. Here the Canadian Division was in the trenches which went through Kersselaere along the Gravenstafel ridge to a point adjacent to the cross-roads at Broodseinde, where the 28th Division under General Bulfin held the line as far as the outer, the eastern, edge of the Polygon Wood. Here the 27th Division under General Snow took over the line which bent back westward down to where the 5th Division was in position about Hill 60. This, then, was the famous salient of Ypres. It was in the northern part that the Germans launched their first gas attack, and one can imagine with what eager expectation their gas engineers throughout that fine April day fingered the taps of the cylinders embedded in front of their trenches, where our outlook men had observed them working for several weeks before. We have never heard the French version of what happened after 5.15 on the evening of April 22, when the fatal greenish-yellow cloud, the significance of which no man could fathom at that time, rising to about man’s height, began to roll sluggishly forward from the white and blue sandbags marking the German line. We only know that our artillery observation officers in their different coigns of vantage in this region saw a mysterious greenish haze hovering over the French lines, and that presently down all the roads leading from the canal to Ypres and Vlamertinghe and Poperinghe a stream of French infantry and Turcos appeared, most of them with terror in their faces, with streaming eyes and gasping breath, in the grip of a horror they feared because they did not understand it.