On this day the cavalry under Gen. Allenby reached the neighborhood of Braine and did good work in clearing the town and the high ground beyond it of strong hostile detachments. The Queen's Bays are particularly mentioned by the General as having assisted greatly in the success of this operation. They were well supported by the Third Division, which on this night bivouacked at Brenelle, south of the river. The Fifth Division approached Missy, but were unable to make headway. The First Army Corps reached the neighborhood of Vauxcere without much opposition. In this manner the battle of the Aisne commenced. 2. The Aisne Valley runs generally east and west, and consists of a flat-bottomed depression of width varying from half a mile to two miles, down which the river follows a winding course to the west, at some points near the southern slopes of the valley and at others near the northern. The high ground both on the north and south of the river is approximately 400 feet above the bottom of the valley, and is very similar in character, as are both slopes of the valley itself, which are broken into numerous rounded spurs and re-entrants. The most prominent of the former are the Chivre spur on the right bank and Sermoise spur on the left. Near the latter place the general plateau, on the south is divided by a subsidiary valley of much the same character, down which the small River Vesle flows to the main stream near Sermoise. The slopes of the plateau overlooking the Aisne on the north and south are of varying steepness, and are covered with numerous patches of wood, which also stretch upward and backward over the edge on to the top of the high ground. There are several villages and small towns dotted about in the valley itself and along its sides, the chief of which is the town of Soissons. The Aisne is a sluggish stream of some 170 feet in breadth, but, being 15 feet deep in the centre, it is unfordable. Between Soissons on the west and Villiers on the east (the part of the river attacked and secured by the British forces) there are eleven road bridges across it. On the north bank a narrow-gauge railway runs from Soissons to Vailly, where it crosses the river and continues eastward along the south bank. From Soissons to Sermoise a double line of railway runs along the south bank, turning at the latter place up the Vesle Valley toward Bazoches. The position held by the enemy is a very strong one, either for delaying action or for a defensive battle. One of its chief military characteristics is that from the high ground on neither side can the top of the plateau on the other side be seen, except for small stretches. This is chiefly due to the woods on the edges of the slopes. Another important point is that all the bridges are under direct or high-angle artillery fire.