On the 25th, the right wing of the German army was reported to be advancing, protected by about three divisions of cavalry with supporting artillery. Patrols reached the outskirts of the town soon afterwards.
General Herment executed the orders he had received. Moreover, he knew that the neighbouring town of Maubeuge was holding out with 45,000 men, and that the Belgian army was intact at Antwerp.
On September 2nd, enemy detachments entered Lille, disappearing three days later. The town was only occupied by patrols, who had orders to secure the German right (Von Kluck's army), which was executing its famous flanking movement. Then came the Victory of the Marne. After the German retreat and the indecisive Battle of the Aisne, the enemy began their northward movement known as the "Race for the Sea," the aim of which, on either side, was to turn the adversary's wing.
On October 3rd, Joffre joined the 10th army under General de Maud'huy to reinforce his left and prevent its envelopment. The 21st Army Corps arrived from Champagne, and the 13th Division detrained to the west of the town.
On the morning of the 4th, battalions of Chasseurs, belonging to the 13th Division, received orders to take up positions to the north and east of the town. After spending the night at Armentières, they passed through Lille, where they had an enthusiastic reception.
The 17th Battalion, which was to occupy the suburb of Fives, was met with a sharp fusillade as it left the ramparts. Organizing promptly, it drove the enemy from the railway station and fortifications, capturing a number of machine-guns and prisoners. To the north of the town, the French troops came into contact with German patrols near Wambrechies and Marquette, while the 7th cavalry Division had skirmishes in the neighbourhood of Fouquet.
Meanwhile, the garrison, consisting of territorials and Algerian mounted troops, took up positions to the south of Faches and Wattignies, in liaison, at Ronchin, with other units of the 13th Division. The enemy attacked at this point, and reached the railway.
On the 5th, after a sharp counter-attack, the French took Fives, Hellemmes, Flers, the Fort of Mons-en-Barœul and Ronchin. To the west of the town cavalry engagements took place along the Ypres Canal. On the 6th, the 13th Division left the outskirts of the town, following the 21st Corps in the direction of Artois. Only two battalions of Chasseurs were left in Lille.
On the 7th, the two battalions of Chasseurs rejoined the 13th Division, the defence of Lille being left to the territorials and Algerian troops. On the 9th and 10th, the 2nd cavalry Corps engaged the enemy near Estaires-Merville (between Aire-sur-la-Lys and Armentières), but was unable to open the road to Lille, which was then left to its fate.