The Allied forces were preparing for a major offensive in response to their failure in the Balkans. And while chaos erupted across their colonial possessions, no doubt instigated by the German Reich, and their allies within the Central Powers. Their eyes were once more cast upon Luxembourg.
Having tested the combined defenses of the Royal Belgian Army and the Imperial German Army at Belgium's borders with France, and were once more repelled by their adversaries.
The Allied powers came to the conclusion that if they were to funnel their combined might into Luxembourg, they would be able to push back the Germans and gain a much needed foothold on the western front.
They came to this conclusion specifically because Luxembourg was the weakest of the German defenses in the west. Only a single division stood at its border with France. From the German perspective, creating a failure point in their defense was necessary.