Austria-Hungary declared war with Serbia on 28th July 1914.

Germany pledging its Alliance with Austria-Hungary, the German army invaded Neutral Belgium on August 3rd 1914.

Germany had prepared itself for any future war in the early 20th century nine years earlier with the concept of " Schlieffen Plan" With Russia on the east and the French on the west both countries part of the Anglo-Russian Entente, the Germans had prepared themselves to be fighting on two fronts.