The French town of Maubeuge was a major fort on the French side of the border. With a junction of no fewer than five major railway lines, it was recognized as a key strategic position by both sides; hence the construction of 15 forts and gun batteries ringing it, a total of 435 guns, and a permanent garrison of 35,000 troops. These were further bolstered by the choosing of the town as the advance base of the British Expeditionary Force. However, when these and the French Fifth Army retreated following the events at Charleroi, the town was cut off from allied support, and subsequently besieged on August 25. The German heavy artillery succeeded in demolishing the key forts around the city, and General Joseph Anthelme Fournier, in command of the garrison in the city, surrendered to the Germans some 13 days later.