Why Germany Invaded Belgium -- Twice

In both World Wars, the fighting in the West began with a German invasion of Belgium.

1914: Why
German strategy in the late 19th and early 20th centuries was based on the assumption that, in the event of a war with Russia, Germany would also have to fight France. The result was the Schlieffen Plan, a strategy to knock France out of the war before taking on Russia.

Since losing to Germany in the Franco-Prussian war, the French had been preparing for such an event. They had built sturdy fortifications along their frontier with Germany and had plenty of troops.