On September 3, 1939, France and Great Britain declared war on Germany after the latter invaded Poland, with which they had entered into a military alliance. Fighting the Wehrmacht on their own, the Poles expected their French and British allies to provide strong and immediate assistance. However, after declaring war on the Third Reich, the Western powers only made a semblance of fulfilling their allied duties to Poland. Although the French and British command had overwhelming military superiority over the enemy on the Western Front, it decided to dig in behind the Maginot Line without undertaking any major offensive. No active warfare was waged on the sea or in the air, either.

On September 9, 1939, the French Army launched a limited offensive in the Saarbrucken district. Lasting for just three days, it was more of a demonstration of force than real aid to the Polish Army. Basically, the French and British allies, despite their promises to the Polish government, looked on while Poland was crushed.

After Poland’s collapse in September 1939, the war in Western Europe continued to be waged in a strange manner: Anglo-­French and German troops dug in their heels on the borders without undertaking any offensives.