An effort on the part of the Germans in this direction was not unexpected, since movements of troops and transport behind their front line had been detected for some days. Its peculiar and novel nature, however, was a surprise which was largely responsible for the measure of success achieved. Taking advantage of the fact that at this season of the year the wind not infrequently blows from the north, they secretly brought up apparatus for emitting asphyxiating vapor or gas, and distributed it along the section of their front line opposite that of our allies, west of Langemarck, which faced almost due north. Their plan was to make a sudden onslaught southwestward, which, if successful, might enable them to gain the crossings on the canal south of Bixschoote and place them well behind the British left in a position to threaten Ypres. The attack was originally fixed for Tuesday, the 20th, but since all chances of success depended on the action of the asphyxiating vapor it was postponed, the weather being unfavorable. On Thursday, the 22d, the wind blew steadily from the north, and that afternoon, all being ready, the Germans put their plan into execution. Since then events have moved so rapidly and the situation has moved so frequently that it is difficult to give a consecutive and clear story of what happened, but the following account represents as nearly as can be the general course of events. The details of the gas apparatus employed by them are given separately, as also those of the asphyxiating grenades, bombs, and shells of which they have been throwing hundreds. At some time between 4 and 5 P.M. the Germans started operations by releasing gases with the result that a cloud of poisonous vapor rolled swiftly before the wind from their trenches toward those of the French west of Langemarck, held by a portion of the French Colonial Division. Allowing sufficient time for the fumes to take full effect on the troops facing them, the Germans charged forward over the practically unresisting enemy in their immediate front, and, penetrating through the gap thus created, pressed on silently and swiftly to the south and west. By their sudden irruption they were able to overrun and surprise a large proportion of the French troops billeted behind the front line in this area and to bring some of the French guns as well as our own under a hot rifle fire at close range. The first intimation that all was not well to the north was conveyed to our troops holding the left of the British line between 5 and 6 P.M. by the withdrawal of some of the French Colonials and the sight of the wall of vapor following them. Our flank being thus exposed the troops were ordered to retire on St. Julien, with their left parallel to but to the west of the highroad. The splendid resistance of these troops, who saved the situation, has already been mentioned by the Commander in Chief.