Answer:
After the declarations of war in World War I, the first nation to act was Germany. Germany had developed a military plan known as the Schlieffen Plan, which called for a rapid invasion of France through neutral Belgium in order to quickly defeat France and then turn their attention to Russia in the east.
In order to implement this plan, Germany needed to quickly invade Belgium and secure a path to France. On August 4, 1914, German forces crossed the border into Belgium, violating its neutrality and triggering the entry of Britain into the war.
Germany's decision to invade Belgium was a major turning point in the war and had significant consequences for the course of the conflict. It led to a wider war involving multiple nations and set the stage for years of brutal fighting on the Western Front. The invasion of Belgium also had important diplomatic repercussions, as it violated international law and norms and led to international condemnation of Germany's actions.
Overall, Germany's decision to invade Belgium was a significant moment in the early stages of World War I and helped to shape the course of the conflict in the years to come.