Fall Weiss (1939)

Fall Weiss ("Case White", "Plan White"; German spelling Fall Weiß) was the Nazi strategic plan for the invasion of Poland. The German military High Command finalized its operational orders on 15 June 1939 and the invasion commenced on 1 September, precipitating World War II.

Plan details
The origins of the plan went back to 1928 when Werner von Fritsch started working on it. Fall Weiss was developed primarily by Günther Blumentritt and Erich von Manstein while the two were serving as staff officers under General Gerd von Rundstedt with Army Group South in Silesia.

The plan called for a start of hostilities before the declaration of war. German units were to invade Poland from three directions:
 * Main attack from the German mainland across the western border of Poland.
 * Second route of attack from the north, from the exclave of East Prussia.
 * Tertiary attack by German and allied Slovak units across the border of Slovakia.

All three assaults were to converge on Warsaw, while the main Polish army was to be encircled and destroyed west of the Vistula River.

Fall Weiss was initiated on 1 September 1939, and was the first European military operation of World War II.

Similar plans
Alongside Fall Weiss ("Case White"), German strategists prepared other variants of the plan:
 * Fall Rot ("Case Red") (1935) – the German defense plan in case of an incursion by France following a German invasion of Czechoslovakia.
 * Fall Grün ("Case Green") (1938) – the German plan to invade Czechoslovakia.
 * Fall Gelb ("Case Yellow") (1940) – the German offensive against western Europe.
 * Fall Grün – ("Case Green") (1940) - the German plan to invade Ireland.
 * Fall Blau ("Case Blue") (1942) – the 1942 German strategic summer offensive in southern Russia.
 * Fall Weiss ("Case White") (1943) – a combined Axis operation against the Yugoslav Partisans throughout occupied Yugoslavia.