Between the Wars

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 important stages of interwar diplomacy and international relations included resolutions of wartime issues, such as reparations owed by Germany and boundaries; American involvement in European finances and disarmament projects; the expectations and failures of the League of Nations; the relationships of the new countries to the old; the distrustful relations of the Soviet Union to the capitalist world; peace and disarmament efforts; responses to the Great Depression starting in 1929; the collapse of world trade; The collapse of democratic regimes one by one; the growth of economic autarky; Japanese aggressiveness toward China; Fascist diplomacy, including the aggressive moves by Mussolini's Italy and Hitler's Germany; the Spanish Civil War; the appeasement of Germany's expansionist moves toward the Rhineland, Austria, and Czechoslovakia, and the last, desperate stages of rearmament as the second world war increasingly loomed.

...
Wikipedia