Through late August and early September, the Germans had continued their race through Belgium and Northern France, and the British and French had continued their long retreat. Though the British and French needed to stop the Germans, they were greatly outnumbered by these invaders who had taken a Northernly route through Belgium; the Germans everywhere could swarm around the ends of any French or British army which got in their way, cutting them off in a day or so, and surrounding and capturing them soon thereafter.
So the Entente forces continued their retreat . . . at this point, they could reasonably do only two things: leave token resistance behind them in order to delay the Germans (though doomed to either annihilation or capture); and hope that the Germans made some mistakes in executing their grand plan.
In support of this former option, the French army left a force of over 45,000 men to garrison Maubeuge (Mauberg), France and its outlying forts.
True to form, the Germans simply flowed around the city and forts as they encountered resistance, but left about three corps and plenty of heavy and super-heavy guns in the area to carry Maubege by siege. Though the Germans could continue to flow around the city, it remained far more profitable to them to take it . . . a center of a network of roads, capture of the city would allow their supply line to flow through the area uninterrupted, an advantage of vital importance for the rapidly advancing Germans.
The forts at Maubege, though not nearly as heavily fortified as those in Liége, Beligum, were very tough, and harbored enough artillery and men that it would have been dangerous for the Germans to come too ignore them while flowing through the area.
Though the Germans swept through the area on August 24, their siege force amounted to about 50,000 men, and their guns were considered huge for the time. They were content to let the massive artillery break apart the French defenses as the main line of their advance moved farther and farther into France.
Not until September 5 did the Germans even make a serious attempt to seize the forts with their infantry. By that time, however, the forts’ integrity had been seriously damaged by the German guns, and the forts quickly fell, one by one. The evening of September 6 saw the entire Maubege area surrendered to the Germans, with the final stages taking place on September 7.