One of the main myths surrounding the invasion is that it was the first use of the Blitzkrieg doctrine. Leaving aside the argument over whether 'Blitzkrieg' itself was ever a formalized doctrine in the same way as, say, the Soviet's 'Deep Operations', the Polish campaign does not fit the traditional understanding of how it was used in places like France and Russia - large armored encirclements. The real advancement in warfare demonstrated in the Polish Campaign was the German's use of air power. That crucial third element - tanks - came later.

Manstein's plan only envisioned a support role for tanks, and Guderian - who had spent so much time and effort developing the Panzergruppen - worried over the thought of their unprotected flanks. Also, unlike campaigns such as those in France and Russia where maneuver and encirclement was vital to overcome material differences, the Germans had the numerical upper hand.

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Matthew Cooper writes: "Throughout the Polish Campaign, the employment of the mechanized units revealed the idea that they were intended solely to ease the advance and to support the activities of the infantry…. Thus, any strategic exploitation of the armoured idea was still-born. The paralysis of command and the breakdown of morale were not made the ultimate aim of the … German ground and air forces, and were only incidental by-products of the traditional manoeuvers of rapid encirclement and of the supporting activities of the flying artillery of the Luftwaffe, both of which had as their purpose the physical destruction of the enemy troops. Such was the Vernichtungsgedanke of the Polish campaign.
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John Ellis, writing in Brute Force asserted that "…there is considerable justice in Matthew Cooper's assertion that the panzer divisions were not given the kind of strategic (emphasis in original) mission that was to characterize authentic armoured blitzkrieg, and were almost always closely subordinated to the various mass infantry armies."[86] Zaloga and Madej, in The Polish Campaign 1939, also address the subject of mythical interpretations of Blitzkrieg and the importance of other arms in the campaign. "Whilst Western accounts of the September campaign have stressed the shock value of the panzers and Stuka attacks, they have tended to underestimate the punishing effect of German artillery (emphasis added) on Polish units. Mobile and available in significant quantity, artillery shattered as many units as any other branch of the Wehrmacht."
The result was a far more traditional style of warfare based on attrition and brute force, which cost the Germans relatively heavy casualties compared to larger campaigns.

That leads to a second big myth that should be rectified - that the Poles rolled over. Fall Weiß, which lasted only a week less than Fall Gelb, was actually a very hard fought campaign that only came to a definitive end when the Russians invaded from the East. The Poles were preparing the Romanian Bridgehead, which would have surely prolonged the campaign even more.

How long could the Poles have held out? Would the British and French have ever come through?

As with Western portrayals of Normandy and Market Garden, Poland has been used as a scapegoat for British and French failings. The geopolitics surrounding the Polish defense plan - Plan West - deserves attention.

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The Polish political determination to deploy forces directly at the German-Polish border, based on the British Government's promise to come to Poland's aid in the event of invasion, shaped the country's defence plan, Plan West. Poland's most valuable natural resources, industry and population were located along the western border in Eastern Upper Silesia. Polish policy centred on their protection especially since many politicians feared that if Poland were to retreat from the regions disputed by Germany, Britain and France would sign a separate peace treaty with Germany similar to the Munich Agreement of 1938.[47] The fact that none of Poland's allies had specifically guaranteed Polish borders or territorial integrity certainly did not help in easing Polish concerns. For these reasons, Poland disregarded French advice to deploy the bulk of their forces behind the natural barriers such as the Vistula and San rivers, even though some Polish generals supported it as a better strategy. The West Plan did permit the Polish armies to retreat inside the country, but it was supposed to be a slow retreat behind prepared positions and was intended to give the armed forces time to complete its mobilization and execute a general counteroffensive with the support of the Western Allies.[48]

The British and French estimated that Poland should be able to defend itself for two to three months, while Poland estimated it could do so for at least six months. Poland drafted its estimates based upon the expectation that the Western Allies honor their treaty obligations and quickly start an offensive of their own. In addition, the French and British expected the war to develop into trench warfare much like World War I. The Polish government was not notified of this strategy and based all of its defence plans on promises of quick relief by their Western allies.[49][50]

Polish forces were stretched thinly along the Polish-German border and lacked compact defence lines and good defence positions along disadvantageous terrain. This strategy also left supply lines poorly protected. Approximately one-third of Poland's forces were concentrated in or near the Polish Corridor, leaving them perilously exposed to a double envelopment from East Prussia and the west. Another third were massed in the north-central part of the country, between the major cities of Łódź and Warsaw.[51] The Poles' forward concentration largely forfeited their chance of fighting a series of delaying actions since their army, unlike some of Germany's, traveled largely on foot and lacked the ability to retreat to their defensive positions before being overrun by German mechanized formations.[52]

Although the Polish military had prepared for conflict, the civilian population remained largely unprepared. Polish pre-war propaganda emphasized that that any German invasion would be easily repelled. Consequently, Polish defeats during the German invasion came as a shock to the civilian population, who were largely unprepared.[52] Lacking training for such a disaster the civilian population panicked and retreated east, spreading chaos, lowering troop morale and making road transportation for Polish troops very difficult.