Aftermath of World War I in the context of World War I

Historical regions (or historical areas) are geographical regions which, at some point in history, had a cultural, ethnic, linguistic or political basis, regardless of latter-day borders. There are some historical regions that can be considered as "active", for example: Moravia, which is held by the Czech Republic, is both a recognized part of the country as well as a historical region. They are used as delimitations for studying and analysing social development of period-specific cultures without any reference to contemporary political, economic or social organisations.

Definitions of regions vary, and regions can include macroregions such as Europe, territories of traditional sovereign states or smaller microregional areas. Geographic proximity is generally the required precondition for the emergence of a regional identity. In Europe, regional identities are often derived from the Migration Period but for the contemporary era are also often related to the territorial transformations that followed World War I and those that followed the Cold War.

World War II or the Second World War (1 September 1939 – 2 September 1945) was a global conflict between two coalitions: the Allies and the Axis powers. Nearly all of the world's countries participated, with many nations mobilising all resources in pursuit of total war. Tanks and aircraft played major roles, enabling the strategic bombing of cities and delivery of the first and only nuclear weapons ever used in war. World War II is the deadliest conflict in history, causing the death of 70 to 85 million people, more than half of whom were civilians. Millions died in genocides, including the Holocaust, and by massacres, starvation, and disease. After the Allied victory, Germany, Austria, Japan, and Korea were occupied, and German and Japanese leaders were put on trial for war crimes.

The causes of World War II included unresolved tensions in the aftermath of World War I, the rise of fascism in Europe and militarism in Japan. Key events preceding the war included Japan's invasion of Manchuria in 1931, the Spanish Civil War, the outbreak of the Second Sino-Japanese War in 1937, and Germany's annexations of Austria and the Sudetenland. World War II is generally considered to have begun on 1 September 1939, when Nazi Germany, under Adolf Hitler, invaded Poland, after which the United Kingdom and France declared war on Germany. Poland was divided between Germany and the Soviet Union under the Molotov–Ribbentrop Pact. In 1940, the Soviet Union annexed the Baltic states and parts of Finland and Romania. After the fall of France in June 1940, the war continued mainly between Germany, now assisted by Fascist Italy, and the British Empire, with fighting in the Balkans, Mediterranean, and Middle East, the aerial Battle of Britain and the Blitz, and the naval Battle of the Atlantic. Through campaigns and treaties, Germany gained control of much of continental Europe and formed the Axis alliance with Italy, Japan, and other countries. In June 1941, Germany invaded the Soviet Union, opening the Eastern Front and initially making large territorial gains.

The Russian Revolution was a period of political and social change in Russia, starting in 1917. This period saw Russia abolish its monarchy and adopt a socialist form of government following two successive revolutions and a civil war. It can be seen as the precursor for other revolutions that occurred in the aftermath of World War I, such as the German Revolution of 1918–1919. The Russian Revolution was a key event of the 20th century.

The Russian Revolution was inaugurated with the February Revolution in 1917, in the midst of World War I. With the German Empire inflicting defeats on the front, and increasing logistical problems causing shortages of bread and grain, the Russian Army was losing morale, with large scale mutiny looming. Officials were convinced that if Tsar Nicholas II abdicated, the unrest would subside. Nicholas stepped down on 15 March [O.S. 2 March], ushering in a provisional government led by the Duma (parliament). During the unrest, Soviet councils were formed by locals in Petrograd (now Saint Petersburg) that initially did not oppose the new government; however, the Soviets insisted on their influence in the government and control over militias. By March, Russia had two rival governments. The Provisional Government held state power in military and international affairs, whereas the network of Soviets held domestic power. Critically, the Soviets held the allegiance of the working class, and urban middle class. There were mutinies, protests and strikes. Socialist and other leftist political organizations competed for influence within the Provisional Government and Soviets. Factions included the Mensheviks, Social Revolutionaries, Anarchists, and the Bolsheviks, a far-left party led by Vladimir Lenin.

Hussein bin Ali al-Hashimi (Arabic: ٱلْحُسَيْن بِن عَلِي ٱلْهَاشِمِي, romanized: al-Ḥusayn bin 'Alī al-Hāshimī pronunciation; 1 May 1854 – 4 June 1931) was a Hejazi leader from the Banu Qatadah branch of the Banu Hashim clan who was the Sharif and Emir of Mecca from 1908 and, after proclaiming the Great Arab Revolt against the Ottoman Empire, King of the Hejaz, even if he refused this title, from 1916 to 1924. He proclaimed himself Caliph after the abolition of the Ottoman Caliphate in 1924 and stayed in power until 1925 when Hejaz was invaded by the Sultanate of Nejd. His Caliphate was opposed by the British and French empires, the Zionists and the Wahhabis alike. However, he received support from a large part of the Muslim population of that time and from Mehmed VI. He is usually considered as the father of modern pan-Arabism.

In 1908, in the aftermath of the Young Turk Revolution, Hussein was appointed Sharif of Mecca by the Ottoman sultan Abdul Hamid II. His relationship with the Ottoman government deteriorated after the Committee of Union and Progress took power, particularly because of their policies of Turkification and persecution of ethnic minorities, including Arabs. In 1916, with the promise of British support for Arab independence, although it is debated as to what extent the British were influential in his choice, he proclaimed the Arab Revolt against the Ottoman Empire, accusing the Committee of Union and Progress of violating tenets of Islam and limiting the power of the sultan-caliph. While his armies, led by his sons, were engaged in fighting the Ottoman and German troops in the Middle East, Hussein supported the Armenians during the Armenian genocide and saved up to 4,000 of them. In the aftermath of World War I, Hussein refused to ratify the Treaty of Versailles, in protest of the Balfour Declaration, a document supporting the Jewish settlers in Palestine, and the establishment of British and French mandates in Syria, Iraq, and Palestine. His sons Faisal and Abdullah were made rulers of Iraq and Transjordan respectively in 1921.

Surrealism is an art and cultural movement that developed in Europe in the aftermath of World War I in which artists aimed to allow the unconscious mind to express itself, often resulting in the depiction of illogical or dreamlike scenes and ideas. Its intention was, according to leader André Breton, to "resolve the previously contradictory conditions of dream and reality into an absolute reality, a super-reality", or surreality. It produced works of painting, writing, photography, theatre, filmmaking, music, comedy and other media as well.

Works of Surrealism feature the element of surprise, unexpected juxtapositions and non sequitur. However, many Surrealist artists and writers regard their work as an expression of the philosophical movement first and foremost (for instance, of the "pure psychic automatism" Breton speaks of in the first Surrealist Manifesto), with the works themselves being secondary, i.e., artifacts of surrealist experimentation. Leader Breton was explicit in his assertion that Surrealism was, above all, a revolutionary movement. At the time, the movement was associated with political causes such as communism and anarchism. It was influenced by the Dada movement of the 1910s.

The revolutions of 1917–1923 were a revolutionary wave that included political unrest and armed revolts around the world inspired by the success of the Russian Revolution and the disorder created by the aftermath of World War I. The uprisings were mainly socialist or anti-colonial in nature. Most socialist revolts failed to create lasting socialist states. The revolutions had lasting effects in shaping the future European political landscape, with, for example, the collapse of the German Empire and the dissolution of Austria-Hungary.

World War I mobilized millions of troops, reshaped political powers and drove social turmoil. From the turmoil outright revolutions broke out, massive strikes occurred, and many soldiers mutinied. In Russia, the Tsar Nicholas II abdicated during the February Revolution. The short-lived liberal Russian Provisional Government was formed, but it was overthrown by the Bolsheviks in the October Revolution, which triggered the bloody Russian Civil War. Many French soldiers mutinied in 1917 and refused to engage the enemy. In Bulgaria, many troops mutinied, and the Bulgarian Tsar stepped down. Mass strikes and mutinies occurred in Austria-Hungary, and the Habsburg monarchy collapsed. In Germany, the November Revolution led to the end of the German Empire. Italy faced various mass strikes. Turkey experienced a successful war of independence. Ireland was partitioned and the Irish Free State was created. Across the world, various other protests and revolts occurred.

The Greek genocide (Greek: Γενοκτονία των Ελλήνων, romanized: Genoktonía ton Ellínon), which included the Pontic genocide, was the systematic killing of the Christian Ottoman Greek population of Anatolia, which was carried out mainly during World War I and its aftermath (1914–1922) – including the Turkish War of Independence (1919–1923) – on the basis of their religion and ethnicity. It was perpetrated by the government of the Ottoman Empire led by the Three Pashas and by the Government of the Grand National Assembly led by Mustafa Kemal Atatürk, against the indigenous Greek population of the Empire. The genocide included massacres, forced deportations involving death marches through the Syrian Desert, expulsions, summary executions, and the destruction of Eastern Orthodox cultural, historical, and religious monuments. Several hundred thousand Ottoman Greeks died during this period. Most of the refugees and survivors fled to Greece (adding over a quarter to the prior population of Greece). Some, especially those in Eastern provinces, took refuge in the neighbouring Russian Empire.

By late 1922, most of the Greeks of Asia Minor had either fled or had been killed. Those remaining were transferred to Greece under the terms of the later 1923 population exchange between Greece and Turkey, which formalized the exodus and barred the return of the refugees. Other ethnic groups were similarly attacked by the Ottoman Empire during this period, including Assyrians and Armenians, and some scholars and organizations have recognized these events as part of the same genocidal policy.

The Greco-Turkish War of 1919–1922 was fought between Greece and the Turkish National Movement during the partitioning of the Ottoman Empire in the aftermath of World War I, between 15 May 1919 and 14 October 1922. This conflict was a part of the Turkish War of Independence.

The Greek campaign was launched primarily because the western Allies, particularly British prime minister David Lloyd George, had promised Greece territorial gains at the expense of the Ottoman Empire, recently defeated in World War I. Greek claims stemmed from the fact that Western Anatolia had been part of Ancient Greece and the Byzantine Empire before the Turks conquered the area in the 12th–15th centuries. The armed conflict started when the Greek forces landed in Smyrna (now İzmir), on 15 May 1919. They advanced inland and took control of the western and northwestern part of Anatolia, including the cities of Manisa, Balıkesir, Aydın, Kütahya, Bursa, and Eskişehir. Their advance was checked by Turkish forces at the Battle of the Sakarya in 1921. The Greek front collapsed with the Turkish counter-attack in August 1922, and the war effectively ended with the recapture of Smyrna by Turkish forces and the great fire of Smyrna.

The Pontic Greek genocide, or the Pontic genocide (Greek: Γενοκτονία των Ελλήνων του Πόντου), was the deliberate and systematic destruction of the indigenous Greek community in the Pontus region (the northeast of modern Turkey) in the Ottoman Empire during World War I and its aftermath.

The Pontic Greeks had a continuous presence in the Pontus region from at least 700 BC, over 2,500 years ago. Following the Ottoman conquest of the Empire of Trebizond in 1461, the area came under the control of the Ottoman Empire. The rise of Turkish nationalism at the beginning of 20th century dramatically increased anti-Greek sentiment within the Ottoman Empire. The genocide began in 1914 by the Young Turk regime, which was led by the Three Pashas, and, after a short interwar pause in 1918–1919, continued into 1923 by the Kemalist regime which was led by Mustafa Kemal Pasha. Both nationalist movements massacred the Pontians and deported them to the interior regions of Anatolia. This resulted in approximately 350,000 deaths – about half of the pre-genocide Pontic population.

The history of the Jews in Poland dates back at least 1,000 years. For centuries, Poland was home to the largest and most significant Jewish community in the world. Poland was a principal center of Jewish culture, because of the long period of statutory religious tolerance and social autonomy which ended after the Partitions of Poland in the 18th century. During World War II there was a nearly complete genocidal destruction of the Polish Jewish community by Nazi Germany and its collaborators of various nationalities, during the German occupation of Poland between 1939 and 1945, called the Holocaust. Since the fall of communism in Poland, there has been a renewed interest in Jewish culture, featuring an annual Jewish Culture Festival in Kraków, new study programs at Polish secondary schools and universities, and the opening of Warsaw's Museum of the History of Polish Jews.

From the founding of the Kingdom of Poland in 1025 until the early years of the Polish–Lithuanian Commonwealth created in 1569, Poland was the most tolerant country in Europe. Poland became a shelter for Jews persecuted and expelled from various European countries and the home to the world's largest Jewish community of the time. According to some sources, about three-quarters of the world's Jews lived in Poland by the middle of the 16th century. With the weakening of the Commonwealth and growing religious strife (due to the Protestant Reformation and Catholic Counter-Reformation), Poland's traditional tolerance began to wane from the 17th century. After the Partitions of Poland in 1795 and the destruction of Poland as a sovereign state, Polish Jews became subject to the laws of the partitioning powers, including the increasingly antisemitic Russian Empire, as well as Austria-Hungary and Kingdom of Prussia (later a part of the German Empire). When Poland regained independence in the aftermath of World War I, it was still the center of the European Jewish world, with one of the world's largest Jewish communities of over 3 million. Antisemitism was a growing problem throughout Europe in those years, from both the political establishment and the general population. Throughout the interwar period, Poland supported Jewish emigration from Poland and the creation of a Jewish state in Palestine. The Polish state also supported Jewish paramilitary groups such as the Haganah, Betar, and Irgun, providing them with weapons and training.

The Roaring Twenties, sometimes stylized as Roaring '20s, refers to the 1920s decade in music and fashion, as it happened in Western society and Western culture. It was a period of economic prosperity with a distinctive cultural edge in the United States and internationally, particularly in major cities such as Berlin, Buenos Aires, Chicago, London, Los Angeles, Mexico City, New York City, Paris, and Sydney. In France, the decade was known as the années folles ('crazy years'), emphasizing the era's social, artistic and cultural dynamism. Jazz blossomed, the flapper redefined the modern look for British and American women, and Art Deco peaked.

The social and cultural features known as the Roaring Twenties began in leading metropolitan centers and spread widely in the aftermath of World War I. The spirit of the Roaring Twenties was marked by a general feeling of novelty associated with modernity and a break with tradition, through modern technology such as automobiles, moving pictures, and radio, bringing "modernity" to a large part of the population. Formal decorative frills were shed in favor of practicality in both daily life and architecture. At the same time, jazz and dancing rose in popularity, in opposition to the mood of World War I. As such, the period often is referred to as the Jazz Age.

Historical regions (or historical areas) are geographical regions that had a cultural, ethnic, linguistic or political significance as distinct entities at some point in recorded history, regardless of latter-day borders and administrative divisions. There are some historical regions that can be considered as "active", for example: Moravia, which is held by the Czech Republic, is both a recognized contemporary region of the country as well as a historical one. They are used as delimitations for studying and analysing social development of period-specific cultures without any reference to contemporary political, economic or social organisations.

Definitions of regions vary, and regions can include macroregions such as Europe, territories of traditional sovereign states or smaller microregional areas. Geographic proximity is generally the required precondition for the emergence of a regional identity. In Europe, regional identities are often derived from the Migration Period but for the contemporary era are also often related to the territorial transformations that followed World War I and those that followed the Cold War.