World War II Day by Day

London, England · March 31, 1939

On this date in 1939, two weeks after Ger­man troops entered Prague and all of Czecho­slo­va­kia fell under the Ger­man boot, the Brit­ish govern­ment, followed a few days later by the French, pledged to guar­an­tee the inde­pen­dence (though inter­estingly not the terri­torial integ­rity) of Poland. A week later the three states an­nounced a for­mal alli­ance when Polish Foreign Minister Józef Beck visited London.

That the West­ern demo­cra­cies would guar­an­tee Poland’s inde­pen­dence so en­raged Adolf Hitler that he told commanders of his Wehr­macht (German armed forces) to begin stra­tegic plan­ning for Fall Weiss (Oper­a­tion White), the de­struc­tion of Poland, with a pro­vi­sional start date of Septem­ber 1, 1939. A defeated Poland would elim­i­nate the “Free City of Dan­zig” (German, Freie Stadt Dan­zig), con­sisting of the Bal­tic sea­port of Dan­zig (today’s Gdańsk) and sur­rounding areas, which were roughly 95 per­cent ethnic Ger­man. This geo­graphi­cal oddity of the 1919 Ver­sailles Peace Treaty was admin­is­tered by a League of Nations high com­mis­sioner (at the time, a Swiss), and most Germans found Dan­zig’s exis­tence a vexa­tion because it and the so-called Polish Corri­dor split East Prus­sia from West Prus­sia and the rest of Nazi Ger­many (see map). Ger­man units were to in­vade Poland from three direc­tions: the main attack from Ger­many across the west­ern Polish border, a second route from the East Prus­sian en­clave, and a third attack by Ger­man and allied Slo­vak units from the Czech puppet state (since March 14, 1939) of Slo­va­kia. All three assaults were to con­verge on War­saw, the Polish capital.

Fall Weiss was the first Euro­pean mili­tary oper­a­tion of World War II. It would be six years of bru­tal occu­pa­tion and the death of four mil­lion Polish civil­ians, three-quarters of them Jews who died in con­cen­tra­tion camps or gas cham­bers, before the last units of the Wehr­macht were swept from Polish soil. As for Dan­zig itself, many of its resi­dents perished or fled west­ward ahead of the Soviet on­slaught and the city’s de­struc­tion and con­quest by the Red Army in March 1945. After the war most of the re­maining eth­nic Ger­mans were forcibly ex­pelled. The city was sub­se­quently placed under Polish admin­is­tra­tion by the Allied Pots­dam Agree­ment (August 1, 1945), and Poles from Cen­tral and Soviet-an­nexed East­ern Poland were brought in to replace the German population.

German Conquest of Poland, September 1 to October 6, 1939

Above: Map of Danzig (“Free City of Dan­zig,” pre­sent-day Gdańsk) and Poland’s corri­dor to the Baltic Sea (“Polish Corri­dor”) squeezed be­tween Ger­man West and East Prus­sia on the eve of war, 1939. The Memel Terri­tory (today’s Kalinin­grad Oblast) was retrans­ferred by an in­tim­i­dated Lithu­ania to Nazi Ger­many on March 23, 1939. This event proved to be the last of a series of blood­less annex­a­tions of terri­tories sep­a­rated from Ger­many by the 1919 Treaty of Versailles.

Left: German troops remove Polish insignia at the Polish-Danzig border near Sopot (German, Zoppot), September 1, 1939.

Right: German and Slovak soldiers pose with civilians in Komańcza, Southeastern Poland, September 1939.

Left: German cavalry and motorized units enter Poland from East Prussia, 1939.

Right: The Polish Royal Castle in Warsaw on fire after being shelled by Germans, Septem­ber 17, 1939. On Septem­ber 26 German troops captured three key forts defending Warsaw and entered the capital the next day.

Silent German Propaganda Film “Liberation” of Danzig and Wehrmacht’s Assault on Poland, September 1939