The British attack began at daybreak on October 13. It was a day of rain and fog, one of those fogs which, in autumn, cover these flats with an almost impenetrable mist. Such conditions rendered movement over the low-lying sodden country slow. On the other hand, as against the British troops moving to the attack the conditions put the German guns out of action, and, what was not less material, they concealed the movements of the Allied cavalry. For by this time the French horse, under the command of General Conneau had arrived, and the plan of battle was that the French cavalry should assault and turn the left of the German position at Nieppe, on the main road from Bailleul to Armentières, thus cutting off the enemy from Lille, while the British cavalry attacked Berthen. In the meantime, the main assault would be delivered by the infantry against Bailleul, the centre of the hostile position. Throughout the 13th the fighting raged round Fletre and Meteren. Both places were taken. Meteren was stormed in an onset which at nightfall drove the Germans who were holding it in a ragged rout to Bailleul. General Pulteney decided at once to follow up this advantage. An advance on Bailleul was immediately begun. All this while the cavalry on both wings had been active. At daybreak on October 14 the British horse broke into Berthen, and despite a bitter resistance drove the Germans out, and began to roll up their flank on that side. The French cavalry had got astride of the Armentières road. Realising that their whole force was in danger of being rounded up, the Germans took the chance offered by darkness, intensified by heavy rain, to beat a precipitate retreat. When the British infantry reached Bailleul, they found the town evacuated. These operations opened up the way to Lys, and the 3rd Corps advanced on October 15 to the line of that river extending from Armentières to near Laventie. They thus came into line with the 2nd Corps, which, driving the Germans off the main road from La Bassee to Estaires, an important road junction on the Lys two miles above Sailly, had pushed on to Fournes. At that place, four miles east of Neuve Chapelle, and not more than seven from the centre of Lille, they cut the German communications between Lille and La Bassee. Thus, at the end of four days, the British were both at Armentières and at Fournes, within seven miles of Lille, and formed with Laventie as the base of it, a front of almost a right angle, the apex pointing westward. At the same time the cavalry had received orders to continue their drive from Berthen across the country and down the valley of the Lys towards Menin.[4] In those four days the Germans had been driven back some twenty miles. Decidedly the surprise provided for them by the British army had been anything but agreeable.