The great battle was now ebbing away into a series of lesser engagements. As we shall learn later, the Allies had begun to make a big thrust near Festubert and towards Lens. The Germans had been obliged to send some of their heavy guns to the south, and the artillery fire on the Ypres salient consequently slackened. But before the battle ended the Germans made one more attempt--and this the most terrible of all--to shatter our lines. Again they used the foul weapon by which they had won ground at the outset of the struggle. On the early morning of Monday, 24th May, when the sky was cloudless and a light north-easterly breeze was blowing, they released gas against our front from Shell-trap Farm to the lake. The wind carried the poisonous vapour towards the south-west, and it rolled over nearly five miles of our trenches in a cloud which in some places was forty feet high. For four and a half hours the gas surged towards us. Where our men were quick to don their respirators, they were able to hold their ground; but where there was delay, they suffered horribly. After the gas came a violent bombardment from three points of the compass, and in various places our line was pushed in until three dangerous salients appeared. British steadfastness, however, prevailed. Except in two places, our lines remained intact. The 9th Argyll and Sutherland Highlanders, the 2nd Royal Irish, and the 9th Lancers lost very heavily. Amongst those who fell was Captain Francis Grenfell, who had already won the Victoria Cross for a splendid deed of pluck and coolness, which I described on page 88 of our second volume. * * * * * The Second Battle of Ypres was over. It was not so full of danger to us as the first battle, but it will be ever memorable because, for the first time in the warfare of civilized men, a foul and deadly weapon had been used. You must have noticed, in reading these pages, how the Germans relied on machinery to overcome us. High-explosive shells and poison gas--these were the weapons which they believed would give them victory. During the Second Battle of Ypres the German infantry made few serious attacks, and when they did so they were almost destroyed to a man. Cannot you imagine the anguish of our brave fellows assailed by gas and shell fire and unable to reach their foes? Many of them, goaded to madness, stood up on their parapets and challenged the enemy to come on. Some of the Germans accepted the challenge; our men cheered, and then swept them to earth. It was the Second Battle of Ypres which taught us how inferior we were to the Germans in machinery, and our bitter experience had much to do with the formation of the National Government and the setting up of a Ministry of Munitions.