During the 1939 invasion of Poland, which started World War II in Europe, Stettin was the base for the German 2nd Motorized Infantry Division, which cut across the Polish Corridor and was later used in 1940 as an embarcation point for Operation Weserübung, Germany’s assault on Denmark and Norway.
On 15 October 1939, neighbouring municipalities were amalgamated into Stettin, creating Groß-Stettin with about 380,000 inhabitants in 1940. The city had become the third-largest German city by area, after Berlin and Hamburg.
As the war started, the number of non-Germans in the city increased as slave workers were brought in. The first transports came in 1939 from Bydgoszcz, Toruń and Łódż. They were mainly used in a synthetic silk factory near Szczecin.The next wave of slave workers was brought in 1940, in addition to PoWs who were used for work in the agricultural industry.According to German police reports from 1940, 15,000 Polish slave workers lived within the city.
During the war, 135 forced labour camps for slave workers were established in the city. Most of the 25,000 slave workers were Poles, but Czechs, Italians, Frenchmen and Belgians, as well as Dutch citizens, were also enslaved in the camps.
In February 1940, the Jews of Stettin were deported to the Lublin reservation. International press reports emerged, describing how the Nazis forced Jews, regardless of age, condition and gender, to sign away all property and loaded them on to trains headed to the camp, escorted by members of the SA and SS. Due to publicity given to the event, German institutions ordered such future actions to be made in a way unlikely to attract public notice.

Throughout the war, Stettin (Szczecin) was a major port of disembarcation for Baltic Germans returning to the ‘fatherland’, and later in the war those fleeing the advancing Soviet Red Army.
Allied air raids in 1944 and heavy fighting between the German and Soviet armies destroyed 65% of Stettin’s buildings and almost all of the city centre, the seaport and local industries. Polish Home Army intelligence assisted in pinpointing targets for Allied bombing in the area of Stettin. The city itself was covered by the Home Army’s “Bałtyk” structure and Polish resistance infiltrated Stettin’s naval yards. Other activities of the resistance consisted of smuggling people to Sweden.
In April 1945, Nazi authorities of the city issued an order of evacuation and most of the city’s German population fled. The Soviet Red Army captured the city on 26 April. Stettin was virtually deserted when it fell, with only approx. 6,000 Germans in the city, when Polish authorities tried to gain control.In the following month the Polish administration was forced to leave again twice. Finally the permanent handover occurred on 5 July 1945. In the meantime, part of the German population had returned, believing it might become part of the Soviet occupation zone of Germany and the Soviet authorities had already appointed the German Communists Erich Spiegel and Erich Wiesner as mayors.Stettin is located mostly west of the Oder river, which was considered to become Poland’s new western border, placing Stettin in East Germany. This would have been in accordance with the Potsdam Agreement between the victorious Allied Powers, which envisaged the new border to be in “a line running from the Baltic Sea immediately west of Swinemünde, and thence along the Oder River “. Because of the returnees, the German population of the town swelled to 84,000 again.The mortality rate was at 20%, primarily due to starvation.However, Stettin and the mouth of the Oder River (German: Stettiner Zipfel) became Polish on 5 July 1945, which had been decided in a treaty signed on 26 July 1944 between the Soviet Union and the Soviet-controlled Polish Committee of National Liberation (PKWN) (also known as “the Lublin Poles,” as contrasted with the London-based Polish government-in-exile).On 4 October 1945, the decisive land border of Poland was established west of the 1945 line,but excluded the Police (Pölitz) area, the Oder river itself and the Szczecin port, which remained under Soviet administration.The Oder river was handed over to Polish administration in September 1946, and the port was subsequently handed over between February 1946 and May 1954.

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