Inter-war period

In the context of the history of the 20th century, the interwar period was the period between the end of the First World War (1914–18) and the beginning of the Second World War (1939–45)—the period beginning with the Armistice of 11 November 1918 that concluded the First World War and the ensuing Paris Peace Conference in 1919, and ending in September 1939 with the German invasion of Poland and the start of the World War II.

The years 1919-24 were marked by turmoil as Europe struggled to recover from the devastation of the First World War and the destabilising effects of the loss of four large historic empires: the German Empire, Austro-Hungarian Empire, Russian Empire and the Ottoman Empire. There were numerous new nations in Eastern Europe, most of them small in size. The United States gained dominance in world finance. Thus, when Germany could no longer afford war reparations to Britain, France and other Allies, the Americans came up with the Dawes Plan and Wall Street invested heavily in Germany, which repaid its reparations to nations that, in turn, used the dollars to pay off their war debts to Washington. By the middle of the decade, prosperity was widespread, with the second half of the decade known, especially in Germany, as the "Golden Twenties".

The main institution intended to bring stability was the League of Nations, created in 1919 with the intention of maintaining world security and peace and encouraging economic growth between member countries. The League was undermined from the start by the non-participation of the United States and the Soviet Union, and subsequently by the bellicosity of Mussolini's Italy, Nazi Germany, and Imperial Japan – leading many to question its effectiveness.

...
Wikipedia