[4] The polity was created on 15 November 1920[5] in accordance with the terms of Article 100 (Section XI of Part III)[6] of the 1919 Treaty of Versailles after the end of World War I.

After the German invasion of Poland in 1939, the Nazis abolished the Free City and incorporated the area into the newly formed Reichsgau of Danzig-West Prussia.

[13] Upon the city's capture in the early months of 1945 by the Soviet and Polish troops, a significant number of German inhabitants perished in ill-prepared and over-delayed attempts to evacuate by sea, while the remainder fled or were expelled.

It defended itself through the costly Siege of Danzig in 1577 in order to preserve special privileges, and subsequently insisted on negotiating by sending emissaries directly to the Polish king.

[15] Danzig become known as "the Amsterdam of the East", a wealthy seaport and trading crossroads that linked together the economics of western and eastern Europe, and whose location at where the Vistula flowed into the Baltic led to various powers competing to rule the city.

During the Paris Peace Conference, a commission of inquiry chaired by a British historian, James Headlam-Morley, investigating where the borders between Germany and Poland should be, started to research Danzig's history.

Representatives of various countries took on the role of High Commissioner:[citation needed] The League of Nations refused to let the city-state use the term of Hanseatic City as part of its official name; this referred to Danzig's long-lasting membership in the Hanseatic League:[further explanation needed][26] With the creation of the Free City in the aftermath of World War I a security police force was created on 19 August 1919.

[30] Ultimately the Danzig police participated in the September Campaign, fighting alongside the local SS and the German Army at the city's Polish post office and at Westerplatte.

[30][31] Even though the Free City was formally annexed by Nazi Germany in October 1939, the police force more or less continued to operate as a law enforcement agency.

The police officers in charge of conducting the census were mostly German citizens who were granted Danzig citizenship for the duration of their service, and there were several incidents in which they intimidated the local non-German population.

[42] According to Kijański, many Poles in Danzig did not reveal their nationality in the census as a result of this intimidation, as well as pressure from German employers.

Anyone desiring German citizenship had to leave their property and make their residence outside the Free State of Danzig area in the remaining parts of Germany.

Unlike the Second Polish Republic, which opposed the cooperation of the United Evangelical Church in Poland with EKapU, Volkstag and the Senate of Danzig approved cross-border religious bodies.

The Lutheran congregation of St. Mary's Church could relocate its valuable parament collection and the presbytery granted it on loan to St. Annen Museum in Lübeck after the war.

Other Lutheran congregations of Danzig could reclaim their church bells, which the Wehrmacht had requisitioned as non-ferrous metal for war purposes since 1940, but which had survived, not yet melted down, in storage (e.g. Glockenfriedhof [de]) in the British zone of occupation.

Moreover, the comparatively few Danzig Jews were offered easier refuge in safe countries because of favorable Free City migration quotas.

The Bolivian government of Hernando Siles Reyes wanted to continue the pre-World War I German military mission but the Treaty of Versailles prohibited that.

[109] In December 1925, the Council of the League of Nations agreed to the establishment of a Polish military guard of 88 men on the Westerplatte peninsula to protect the war material depot.

[113] The crisis was resolved when the Free City granted more access rights to the Polish Navy in exchange for a promise to not take the Wicher back into Danzig harbour.

[116][117] After Adolf Hitler came to power in Germany, the Polish military doubled the number of 88 troops at Westerplatte in order to test the reaction of the new chancellor.

[120] Subsequent disputes were resolved in direct negotiations between the Senate and Poland after both had agreed to abstain from further appeals to the International Court in the summer of 1933 and bilateral agreements were concluded.

[121] In the aftermath of the German-Polish Non-Aggression Pact of 1934, Danzig–Polish relations improved and Adolf Hitler instructed the local Nazi government to cease anti-Polish actions.

[126] The Catholic Bishop of Danzig, Edward O'Rourke, was forced to withdraw after he had tried to implement four additional Polish nationals as parish priests in October 1937.

[129] In the middle of August, Beck offered a concession, saying that Poland was willing to give up its control of Danzig's customs, a proposal which caused fury in Berlin.

[130] On 23 August 1939, Albert Forster, the Gauleiter of Danzig, called a meeting of the Senate that voted to have the Free City rejoin Germany, raising tensions to the breaking point.

[133] Instead the British and French applied strong pressure on the Poles not to send in a military force to depose the Danzig government, and appoint a mediator to resolve the crisis.

[134] Originally, it was planned to send the light cruiser Königsberg to Danzig for what was described as a "friendship visit", but it was decided at the last minute that a ship with more firepower was needed, leading to the Schleswig-Holstein with its 11-inch (280 mm) guns being substituted.

[137] Upon anchoring in Danzig harbor, the Schleswig-Holstein ominously aimed its guns at the Polish Military Depot on the Westerplatte peninsula in a provocative gesture that further raised the tensions in the Free City.

[139] In the city itself hundreds of Polish prisoners were subjected to cruel executions and experiments, which included castration of men and sterilization of women considered dangerous to the "purity of Nordic race" and beheading by guillotine.

[142] No formal treaty has ever altered the status of the Free City of Danzig, and its incorporation into Poland has rested upon the general acquiescence of the international community.