The German artillery kept up its almost incessant pounding of the British. In short lulls of the big gun's work the German infantry hurled itself against the trenches on the hill, using hand grenades and bombs. The fight continued until the morning of May 5, 1915, when the wind blew at about four miles an hour from the German trenches. Then a greenish-yellow fog of poisonous gas was released, and soon encompassed the hill. The East Surreys, who were holding the hill, were driven back by the gas, but as soon as the gas passed they charged the Germans who had followed the gas and had taken possession of the hill. Notwithstanding the machine-gun fire which the Germans poured upon them, many of the trenches were retaken by the Surrey soldiers in their first frenzied rush to regain what they had lost because of the gas. The battle ended when there was no hill left. The bombardment and the mines had leveled the mound by distributing it over the surrounding territory. The British, however, were accorded the victory, as they had trenches near where the hill was and made them a part of the base of the salient about Ypres. That town has been likened to the hub of a wheel whose spokes are the roads which lead eastward. It is true that one important road went over the canal, at Steenstraate, but practically all of the highways of consequence went through Ypres. Thus the spokes of the wheel, whose rim was the outline of the salient, were the roads to Menin, Gheluvelt, Zonnebeke, Poelcapelle, Langemarck, and Pilkem. And the railroad to Roulers was also a spoke. Hence all of the supplies for the troops on the salient must pass through Ypres, which made it most desirable for the Germans to take the town. It will be remembered that they had won a place for their artillery early in November, 1914, which gave them an opportunity to bombard Ypres through the winter. On February 1, 1915, a portion of the French troops which had held the salient were withdrawn and their places taken by General Bulfin's Twenty-eighth Division. Thus, by April 20, 1915, that part of the Allies' front was held as follows: From the canal to east of Langemarck was the Forty-fifth Division of the French army, consisting of colonial infantry. On the French right, to the northeast of Zonnebeke, was the Canadian division, under the command of General Alderson, consisting of the Third Brigade, under General Turner, on the left, and the Second Brigade, under General Currie, on the right. The Twenty-eighth Division extended from the Canadian right to the southeast corner of the Polygon Wood. This division comprised the Eighty-third, Eighty-fourth, and Eighty-fifth Brigades in order from right to left. The next section of the salient was held by Princess Patricia's Regiment of the Twenty-seventh Division, which division, under the command of General Snow, guarded the front to the east of Veldhoek along the ridge to within a short distance of Hill 60, where the Fifth