Invasion of Poland time period World War II
None of the parties to the conflict—Germany, the Western Allies or the Soviet Union—expected that the German invasion of Poland would lead to a war that would surpass World War I in its scale and cost. It would be months before Hitler would see the futility of his peace negotiation attempts with the United Kingdom and France, but the culmination of combined European and Pacific conflicts would result in what was truly a "world war". Thus, what was not seen by most politicians and generals in 1939 is clear from the historical perspective: The Polish September Campaign marked the beginning of a pan-European war, which combined with the Japanese invasion of China in 1937 and the Pacific War in 1941 to form the global conflict known as World War II.
The invasion of Poland led Britain and France to declare war on Germany on 3 September. However, they did little to affect the outcome of the September Campaign. No declaration of war was issued by Britain and France against the Soviet Union. This lack of direct help led many Poles to believe that they had been betrayed by their Western allies. British Foreign Secretary Lord Halifax said they were only obligated to declare war on Germany due to the first clause of the Anglo-Polish Agreement in 1939.The different attitude of the Anglo-French allies of Poland towards Nazi Germany and the USSR was argued at this time, for example, by the future head of the British government, Churchill:
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