British declaration of war on Germany (1939)

Negotiations between the Allied powers regarding post-war Europe started on 18 January 1919 in the Salle de l'Horloge at the French Foreign Ministry on the Quai d'Orsay in Paris.

At the time of the armistice, in the first stages of the German Revolution, power had passed provisionally to leaders of the Social Democratic Party, the abdication of the Emperor of Germany was announced on 9 November 1918, and what became known as the Weimar Republic was subsequently established through a constituent national assembly.

The officer class gave little support to the Republic, and Germany was forced to borrow money from the United States and others to pay its war debt, imposed by the Treaty of Versailles.

In early November 1938, the First Vienna Award was signed, allowing Germany to seize the Sudetenland, a German-speaking area of Czechoslovakia which had been a part of the German Empire-allied Austro-Hungarian Empire.

The Polish ambassador in London, Edward Bernard Raczyński, contacted the British Foreign Office to point out that clause 1(b) of the agreement, which concerned an "aggression by a European power" on Poland, should apply to the Soviet invasion.

Foreign Secretary Lord Halifax responded that the obligation of British Government towards Poland arising out of the Anglo-Polish Agreement was restricted to Germany, according to the first clause of the secret protocol.

At the insistence of Joseph Stalin, the post-war Yalta Conference in 1945 sanctioned the formation of a new provisional pro-Communist coalition government in Moscow, which ignored the Polish government-in-exile based in London.