Interwar period

Petroleum-based energy production and associated mechanisation led to the prosperous Roaring Twenties, a time of social and economic mobility for the middle class.

[4] On land, discussions focused on how armoured, mechanised, and motorised forces should be employed, particularly in-relation to the traditional branches of the regular infantry, horse cavalry, and artillery.

[7][8] The military deliberations and controversies characteristic of the interwar period would ultimately find resolution via the events of WWII,[9] which served as a foundation for many of the tenets, doctrines, and strategies of modern warfare.

[10] Overall, the innovations of WWI and the interwar period would see a shift away from traditional line- and front-based warfare and towards a significantly more mobile, mechanised, and asymmetric form of combat.

There were numerous new or restored countries in Southern, Central, and Eastern Europe, some small in size, such as Lithuania and Latvia, and some larger, such as Poland and the Kingdom of Serbs, Croats, and Slovenes.

[11] 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;[12] 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 efforts at economic autarky; Japanese aggressiveness toward China, occupying large amounts of Chinese land, as well as border disputes between the Soviet Union and Japan, leading to multiple clashes along the Soviet and Japanese occupied Manchurian border; fascist diplomacy, including the aggressive moves by Mussolini's Italy and Hitler's Germany; the Spanish Civil War; Italy's invasion and occupation of Abyssinia (Ethiopia) in the Horn of Africa; the appeasement of Germany's expansionist moves against the German-speaking nation of Austria, the region inhabited by ethnic Germans called the Sudetenland in Czechoslovakia, the remilitarisation of the League of Nations demilitarised zone of the German Rhineland region, and the last, desperate stages of rearmament as the Second World War increasingly loomed.

U.S. Secretary of State Charles Evans Hughes sponsored the Washington Naval Conference of 1921 in determining how many capital ships each major country was allowed.

[21] Most independent countries enacted women's suffrage in the interwar era, including Canada in 1917 (though Quebec held out longer), Britain in 1918, and the United States in 1920.

[23]In Europe, according to Derek Aldcroft and Steven Morewood, "Nearly all countries registered some economic progress in the 1920s and most of them managed to regain or surpass their pre-war income and production levels by the end of the decade."

[32] The Weimar Republic in Germany gave way to two episodes of political and economic turmoil, the first culminated in the German hyperinflation of 1923 and the failed Beer Hall Putsch of that same year.

Economic disaster led to a distrust in the effectiveness of democracy and its collapse in much of Europe and Latin America, including the Baltic and Balkan countries, Poland, Spain, and Portugal.

[36] Fascist parties sprang up, attuned to local right-wing traditions, but also possessing common features that typically included extreme militaristic nationalism, a desire for economic self-containment, threats and aggression toward neighbouring countries, oppression of minorities, a ridicule of democracy while using its techniques to mobilise an angry middle-class base, and a disgust with cultural liberalism.

Britain and France effectively controlled the League of Nations, which issued the Lytton Report in 1932, saying that Japan had genuine grievances, but it acted illegally in seizing the entire province.

Prime Minister Tsuyoshi tried to negotiate with China but was assassinated in the May 15 Incident in 1932, which ushered in an era of nationalism and militarism led by the Imperial Japanese Army and supported by other right-wing societies.

Large-scale warfare, known as the Second Sino-Japanese War, began in August 1937, with naval and infantry attacks focused on Shanghai, which quickly spread to other major cities.

In Spain the conservative and Catholic elements and the army revolted against the newly elected government of the Second Spanish Republic, and full-scale civil war erupted.

Fascist Italy and Nazi Germany gave munitions and strong military units to the rebel Nationalist faction, led by General Francisco Franco.

The civil war did not escalate into a larger conflict, but did become a worldwide ideological battleground that pitted all the Communists and many socialists and liberals against Catholics, conservatives and fascists.

[46][47] The changing world order that the war had brought about, in particular the growth of the United States and Japan as naval powers, and the rise of independence movements in India and Ireland, caused a major reassessment of British imperial policy.

[53]: 269–96 The Dominions (Canada, Newfoundland, Australia, New Zealand, South Africa and the Irish Free State) were self-governing and gained semi-independence in the World War, while Britain still controlled foreign policy and defence in all except Ireland.

Under the Treaty of Rapallo, Germany accorded the Soviet Union de jure recognition, and the two signatories mutually agreed to cancel all pre-war debts and renounced war claims.

[65] After establishing the "Rome-Berlin Axis" with Benito Mussolini, and signing the Anti-Comintern Pact with Japan – which was joined by Italy a year later in 1937 – Hitler felt able to take the offensive in foreign policy.

However, hardly six months after the Munich Agreement, in March 1939, Hitler used the smouldering quarrel between Slovaks and Czechs as a pretext for taking over the rest of Czechoslovakia as the Protectorate of Bohemia and Moravia.

The aim of Italian policy, which cannot have, and does not have continental objectives of a European territorial nature except Albania, is first of all to break the bars of this prison ... Once the bars are broken, Italian policy can only have one motto—to march to the oceans.In the Balkans, the Fascist regime claimed Dalmatia and held ambitions over Albania, Slovenia, Croatia, Bosnia and Herzegovina, Macedonia, and Greece based on the precedent of previous Roman dominance in these regions.

[71] In both 1932 and 1935, Italy demanded a League of Nations mandate of the former German Cameroon and a free hand in the Ethiopian Empire from France in return for Italian support against Germany in the Stresa Front.

[77] After the victory by Franco and the Nationalists in the war, Allied intelligence was informed that Italy was pressuring Spain to permit an Italian occupation of the Balearic Islands.

[78] After Great Britain signed the Anglo-Italian Easter Accords in 1938, Mussolini and Foreign Minister Galeazzo Ciano issued demands for concessions in the Mediterranean by France, particularly regarding French Somaliland, Tunisia and the French-run Suez Canal.

[79] Mussolini professed that Italy would only be able to "breathe easily" if it had acquired a contiguous colonial domain in Africa from the Atlantic to the Indian Oceans, and when ten million Italians had settled in them.

[83] In the Albanian Kingdom, Zog I introduced new civil codes, constitutional changes and attempted land reforms, the latter which was largely unsuccessful due to the inadequacy of the country's banking system that could not deal with advanced reformist transactions.

[84] Ethnic integration and assimilation was a major problem faced by the newly formed post-World War I Balkan states, which were compounded by historical differences.