Since the earliest days of the war, German military command had been focused on capturing the Belgian city of Liège. Located only about a dozen miles West of northern Germany, Liège and its fortifications commanded a strategic intersection of rivers, bridges and roads vitally important to the success of the German war plan,. This plan called for a rapid advance through Belgium en route to northern France, which had been left mostly undefended.
If Liège could be taken, then troops and supplies could funnel unimpeded through Belgium into the main German line of advance.
For as long as Liège remained in Belgian hands, however, the German supply line would have to make lengthy detours around the city, a severe handicap which would slow the German advance into France.
Unable to simply seize the city from the Belgians, the Germans settled down to a siege, even bringing in massive pieces of artillery for the reduction of the Liège forts. Since then, the siege had quickly moved towards its end:
August 13 saw Fort Chaudfontaine surrender, only 76 of its original 408 members were still alive. Two other forts, similarly devastated, also surrendered.
On August 15, Fort Lonçin took a 420mm artillery hit directly to its ammunition bunker, utterly destroying the viability of the fort. The Belgian commander, General Gérard Leman, was pulled from the wreckage, saying later to his German captors: “I ask you to bear witness that you found me unconscious.”
Though a few forts remained, their position rendered them unable to hinder the German advance. These would be dealt with at leisure. The siege was over. German troops and supplies began to pour through the area. The German right-wing, the all-important scythe-tip of the Schlieffen plan, raced through Belgium