Just two things... After the Franco-Prussian war the British were forced to act in case of another European war with Germany because they could not accept Germany becoming the dominant continental power. So the invasion of Belgium was a welcome excuse, at least to the military wo had been planning with France since a long time, to legitimate British involvement. Secondly, I dare say that the Germans failed in almost every way during the opening days of the war due to a multitude of reasons, ranging from trying to force their massive armies between the narrow strip of land between the Netherlands, Germany and Belgium, the unexpected Belgian resistance at Liege and the delay this caused, the lack of an appropriate answer to this and the violation of Dutch neutrality when trying to counter the resistance at Liege.