Exactly 70 years ago, German troops entered Poland, triggering the armed conflict of World War II. This invasion follows Poland's refusal to cede Danzig to the Reich and under the poor pretext of responding to a provocation actually orchestrated by the SS themselves (the Gleiwitz incident fomented by Himmler). The Polish army bravely resisted, but eventually gave in under pressure from the Wehrmacht and the Soviet invasion of its eastern border on September 17. Poland surrendered on September 28 following the siege of Warsaw.
This success allows Germany to validate on the ground the formidable effectiveness of the Blitzkrieg theory against an adversary with substantial defenses and to convince its own generals of the military's ability to confront European powers.
This is the first Nazi conquest by arms after those carried out on diplomatic ground following successive bluffing blows led by Adolph Hitler (Austrian Anschluss, attachment of the Sudetenland and annexation of Czechia).
It definitively marks the end of hopes for peace in Europe and underlines the dismal failure of the appeasement policy advocated by Chamberlain - and to a lesser extent, Daladier - since Hitler's accession to power in 1933. It is moreover this same policy which, cruelly lacking in firmness and clarity in the eyes of the world, led the Soviets to sign a pact with the devil on September 23, 1939 ... an agreement which paradoxically opened wide the doors of Central Europe and from the West to the armies of the 3rd Reich.
The entry into the war of France and England on September 3, 1939 and under the pressure of their respective peoples is then inevitable, but unfortunately very weak: no offensive initiative apart from Gamelin's visit to the German Saar from 6 to September 13, 1939. Anyway, it is then probably too late to hope to counter the Nazi surge ...
The hell of the fighting has only just (re) begun in Europe, twenty years after the signing of the Treaty of Versailles, which sowed the seeds of it, with its conditions deemed particularly humiliating in Germany.