Total war and political instability in the first half of the 20th century gave way to a polarized state order during the Cold War and eventually to efforts at transnational union.
European politics and diplomacy in the 20th century were defined by total war and its consequences. World War I destroyed the balance of power, and the Treaty of Versailles, which ended the war, created unstable conditions in which extremist ideologies emerged that challenged liberal democracy and the postwar settlement. In Russia, hardships during World War I gave rise to a revolution in 1917. The newly established, postwar democracies in central and eastern Europe were too weak to provide stability either internally or in the European state system, especially during the Great Depression of the 1930s. The League of Nations, established after the war to employ collective security in the interests of peace, could not manage the international tensions unleashed by World War I. The breakdown of the settlement led to World War II, a conflict even more violent than World War I. During this second great war, the combatants engaged in wholesale destruction of cities, deliberate attacks on civilians, and the systematic destruction of their enemies’ industrial complexes. The Nazi government in Germany undertook the annihilation of Jews from the whole continent (the Holocaust), as well as the murder of other targeted groups of Europeans. At the end of the war, the economic and political devastation left a power vacuum that facilitated the Cold War division of Europe.
During the 20th century, European imperialism, power, and sense of superiority reached both its apogee and nadir. In the first half of the century, nations extended their control and influence over most of the non-Western world, often through League of Nations’ mandates. The idea of decolonization was born early in the century with the formation of movements seeking rights for indigenous peoples; the material and moral destruction of World War II made the idea a reality. After the war, regions colonized and dominated by European nations moved from resistance to independence at differing rates and with differing consequences. Yet even after decolonization, neocolonial dependency persisted, and millions of people migrated to Europe as its economy recovered from the war. This immigration created large populations of poor and isolated minorities, which occasionally rioted because of discrimination and economic deprivation. As European governments tried to solve these problems, the apparently permanent presence of the immigrants challenged old notions of European identity.
The uneasy alliance between Soviet Russia and the West during World War II gave way after 1945 to a diplomatic, political, and economic confrontation between the democratic, capitalist states of Western Europe allied with the United States and the communist bloc of Eastern Europe dominated by the Soviet Union (also known as the Union of Soviet Socialist Republics, or USSR). During the ensuing confrontation between East and West, called the Cold War, relations between the two blocs fluctuated, but one consequence of the conflict was that European nations could not act autonomously in international affairs; the superpowers -- the Soviet Union and the United States -- controlled international relations in Europe.
Nonetheless, the Cold War promoted political and economic unity in Western Europe, leading to the establishment of a succession of ever-more comprehensive organizations for economic cooperation. In 1957, six countries formed the Common Market, which soon began to expand its membership to include other European states. The success of the Common Market inspired Europeans to work toward a closer political and economic unity, including a European executive body and Parliament. The founding of the European Union in 1991 at Maastricht included the agreement to establish the euro as a common currency for qualifying member-states. Following a series of largely peaceful revolutions in 1989, culminating in the collapse of the Soviet Union in 1991, the formerly communist states of Eastern Europe moved toward democracy and capitalist economies, and over time some of these states joined the European Union. One unforeseen consequence of the end of the Cold War was the re-emergence of nationalist movements within states, which led to the Balkan wars in Yugoslavia and tensions among the successor states of the Soviet Union as well as the rebirth of nationalist political parties in Western Europe.
4.1.1: World War I, caused by a complex interaction of long- and short-term factors, resulted in immense losses and disruptions for both victors and vanquished.
4.1.1.A: A variety of factors -- including nationalism, military plans, the alliance system, and imperial competition -- turned a regional dispute in the Balkans into World War I.
4.1.1.B: New technologies confounded traditional military strategies and led to trench warfare and massive troop losses.
4.1.1.C: The effects of military stalemate, national mobilization, and total war led to protest and insurrection in the belligerent nations and eventually to revolutions that changed the international balance of power.
4.1.1.D: The war in Europe quickly spread to non-European theaters, transforming the war into a global conflict.
4.1.1.E: The relationship of Europe to the world shifted significantly with the globalization of the conflict, the emergence of the United States as a world power, and the overthrow of European empires.
4.1.2: The conflicting goals of the peace negotiators in Paris pitted diplomatic idealism against the desire to punish Germany, producing a settlement that satisfied few.
4.1.2.A: Wilsonian idealism clashed with postwar realities in both the victorious and the defeated states. Democratic successor states emerged from former empires and eventually succumbed to significant political, economic, and diplomatic crises.
4.1.2.B: The League of Nations, created to prevent future wars, was weakened from the outset by the nonparticipation of major powers, including the United States, Germany, and the Soviet Union.
4.1.2.C: The Versailles settlement, particularly its provisions on the assignment of guilt and reparations for the war, hindered the German Weimar Republic’s ability to establish a stable and legitimate political and economic system.
4.1.3: In the interwar period, fascism, extreme nationalism, racist ideologies, and the failure of appeasement resulted in the catastrophe of World War II, presenting a grave challenge to European civilization.
4.1.3.A: French and British fears of another war, American isolationism, and deep distrust between Western democratic, capitalist nations, and the authoritarian communist Soviet Union allowed fascist states to rearm and expand their territory.
4.1.3.B: Germany’s Blitzkrieg warfare in Europe, combined with Japan’s attacks in Asia and the Pacific, brought the Axis powers early victories.
4.1.3.C: American and British industrial, scientific, and technological power, cooperative military efforts under the strong leadership of individuals such as Winston Churchill, the resistance of civilians, and the all-out military commitment of the USSR contributed critically to the Allied victories.
4.1.3.D: Fueled by racism and anti-Semitism, Nazi Germany -- with the cooperation of some of the other Axis powers and collaborationist governments -- sought to establish a “new racial order” in Europe, which culminated with the Holocaust.
4.1.4: As World War II ended, a Cold War between the liberal democratic West and the communist East began, lasting nearly half a century.
4.1.4.A: Despite efforts to maintain international cooperation through the newly developed United Nations, deep-seated tensions between the USSR and the West led to the division of Europe, which was referred to in the West as the Iron Curtain.
4.1.4.B: The Cold War played out on a global stage and involved propaganda campaigns; covert actions; limited “hot wars” in Asia, Africa, Latin America, and the Caribbean; and an arms race, with the threat of nuclear war.
4.1.4.C: The United States exerted a strong military, political, and economic influence in Western Europe, leading to the creation of world monetary and trade systems and geopolitical alliances such as NATO.
4.1.4.D: Countries east of the Iron Curtain came under the military, political, and economic domination of the Soviet Union within the Council for Mutual Economic Assistance (COMECON) and the Warsaw Pact.
4.1.4.E: The collapse of the USSR in 1991 ended the Cold War and led to the establishment of capitalist economies throughout Eastern Europe. Germany was reunited, the Czechs and Slovaks parted, Yugoslavia dissolved, and the European Union was enlarged through admission of former Eastern bloc countries.
4.1.5: Nationalist and separatist movements, along with ethnic conflict and ethnic cleansing, periodically disrupted the post-World War II peace.
4.1.6: The process of decolonization occurred over the course of the century with varying degrees of cooperation, interference, or resistance from European imperialist states.
4.1.6.A: At the end of World War I, President Woodrow Wilson’s principle of national self-determination raised expectations in the non-European world for new policies and freedoms.
4.1.7.B: The League of Nations distributed former German and Ottoman possessions to France and Great Britain through the mandate system, thereby altering the imperial balance of power and creating a strategic interest in the Middle East and its oil.
4.1.7.C: Despite indigenous nationalist movements, independence for many African and Asian territories was delayed until the mid- and even late 20th century by the imperial powers’ reluctance to relinquish control, threats of interference from other nations, unstable economic and political systems, and Cold War strategic alignments.