In 1932, [[Adolf Hitler]] was appointed [[List of Chancellors of Germany#Weimar Republic (Reichskanzler) (1919–1933)|Chancellor of the Reich]] following a contentious election. Under Hitler's leadership, the [[Reichstag (Nazi Germany)|Reichstag]] turned the government into an effective [[dictatorship]] under Hitler's oversight on 21 March 1933 with the passage of the [[Enabling Act of 1933]], and the economic hardships were significantly diminished via implementation of new economic and social policies. After five years in power, Hitler [[Anschluss|annexed Austria]], former component of the [[Austro-Hungarian Empire]] (allies of the former [[German Empire]]), into Germany, despite such an act (specifically, "prohibition on the merging of Austria with Germany without the consent of the League of Nations") being banned by both the [[Treaty of Saint-Germain-en-Laye (1919)|Treaty of Saint-Germain-en-Laye]] and 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 was formerly a part of the [[German Empire]]-allied [[Austro-Hungarian Empire]]. Soon after, Germany invaded the rest of Czechoslovakia and also gained [[Memelland]] (part of the former German Empire from 1871-1920) through the [[1939 German ultimatum to Lithuania]].
While some sources claim Hitler still wanted more, to create [[Lebensraum]], or "living space", for Germany, other sources claim evidence of [[Ethnic cleansing|hostility]] on behalf of Polish [[partisan (military)|partisans]] toward [[Germans|ethnic Germans]] in the [[Polish Corridor|Danzig Corridor]] (territory lost to [[Germany]] as a result of the [[Treaty of Versailles]]) which may have served as a motivating factor for the [[Invasion of Poland|German invasion]] (often portrayed as [[propaganda]] to justify German [[expansionism]]).
Two [[Western powers]], the [[United Kingdom]] and [[France]], gave [[Anglo-Polish_military_alliance#British_Guarantee_to_Poland|guarantees]] to [[Poland]] that they would declare war if Polish independence came under threat, as presented in a statement to the [[House of Commons]] by British [[Prime Minister]] [[Neville Chamberlain]] 31 March 1939 (formalized by the British 6 April 1939; not ratified until 4 September 1939 by the French):
{{quote|… in the event of any action which clearly threatened Polish independence, and which the Polish Government accordingly considered it vital to resist with their national forces, His Majesty's Government would feel themselves bound at once to lend the Polish Government all support in their power. They have given the Polish Government an assurance to this effect.
I may add that the French Government have authorised me to make it plain that they stand in the same position in this matter as do His Majesty's Government.[avalon.law.yale.edu/wwii/blbk17.asp Statement by the Prime Minister in the House of Commons on March 31, 1939.]}}
Although they honoured these guarantees by declaring war soon after Germany's [[Invasion of Poland]] on 1 September 1939,{{cite web|last=Rapten|first=Pema Dechen|title=Political Disorder: The Weimar Republic and Revolt 1918-23|url=mtholyoke.edu/~rapte22p/classweb/interwarperiod/politicaldisorder.html|publisher=Mount Holyoke College|accessdate=6 May 2014}} and although the [[Dominions]] of the British Empire quickly followed suit, so little
practical assistance was given to Poland, which was soon defeated, that in its early stages the war declared by Britain and France was described as a [[Phoney War]].