Article: Invasion of Poland
Section: German plan

Question: How many assaults were to converge on Warsaw?

Details of the campaign.
German plan.
The September Campaign was devised by General Franz Halder, chief of the general staff, and directed by General Walther von Brauchitsch, the commander in chief of the upcoming campaign.
It called for the start of hostilities before a declaration of war, and pursued a doctrine of mass encirclement and destruction of enemy forces.
The infantry—far from completely mechanized but fitted with fast moving artillery and logistic support—was to be supported by "Panzers" and small numbers of truck-mounted infantry (the "Schützen" regiments, forerunners of the "panzergrenadiers") to assist the rapid movement of troops and concentrate on localized parts of the enemy front, eventually isolating segments of the enemy, surrounding, and destroying them.
The pre-war "armored idea" (which an American journalist in 1939 dubbed "Blitzkrieg")—which was advocated by some generals, including Heinz Guderian—would have had the armor punching holes in the enemy's front and ranging deep into rear areas; in actuality, the campaign in Poland would be fought along more traditional lines.
This stemmed from conservatism on the part of the German high command, who mainly restricted the role of armor and mechanized forces to supporting the conventional infantry divisions.
Poland's terrain was well suited for mobile operations when the weather cooperated; the country had flat plains with long frontiers totalling almost , Poland's long border with Germany on the west and north—facing East Prussia—extended .
Those had been lengthened by another on the southern side in the aftermath of the Munich Agreement of 1938.
The German incorporation of Bohemia and Moravia and creation of the German puppet state of Slovakia meant that Poland's southern flank was exposed.
Hitler demanded that Poland be conquered in six weeks, but German planners thought that it would require three months.
They intended to fully exploit their long border with the great enveloping manoeuver of "Fall Weiss".
German units were to invade Poland from three directions:
A main attack over the western Polish border.
This was to be carried out by Army Group South commanded by General Gerd von Rundstedt, attacking from German Silesia and from the Moravian and Slovak border: General Johannes Blaskowitz's 8th Army was to drive eastward against Łódź; General Wilhelm List's 14th Army was to push on toward Kraków and to turn the Poles' Carpathian flank; and General Walter von Reichenau's 10th Army, in the centre with Army Group South's armor, was to deliver the decisive blow with a northeastward thrust into the heart of Poland.
A second route of attack from northern Prussia.
General Fedor von Bock commanded Army Group North, comprising General Georg von Küchler's 3rd Army, which was to strike southward from East Prussia, and General Günther von Kluge's 4th Army, which was to attack eastward across the base of the Polish Corridor.
A tertiary attack by part of Army Group South's allied Slovak units from Slovakia.
From within Poland, the German minority would assist by engaging in diversion and sabotage operations through "Volksdeutscher Selbstschutz" units prepared before the war.
All three assaults were to converge on Warsaw, while the main Polish army was to be encircled and destroyed west of the Vistula.
"Fall Weiss" was initiated on 1 September 1939, and was the first operation of Second World War in Europe.