In the wake of the attack on the Austrian heir in June 1914, tensions between the European great powers escalated rapidly. However, the Belgians were not all that concerned: their country was neutral and so did not have to be afraid of becoming involved in a potential conflict. But this was without taking account of the German Schlieffen Plan, a military strategy that anticipated advancing through Belgium on Paris, in the event of a war with France.
On 2 August 1914, a German envoy handed the Belgian government an ultimatum: the German Keizer demanded free passage for his troops through Belgium. The Belgian government, however, refused to accede to the German demand.
They did not have to wait long for Germany's response. On 4 August 1914, German troops invaded Belgium via the Herve plateau. The Belgians were firmly intent on defending their territory, and got the forts around Liege ready at great speed. The first trial of strength of the war on Belgian territory would begin there a day later.