Overview
The Soviet Union, officially the Union of Soviet Socialist Republics (USSR), was a transcontinental country that spanned much of Eurasia from 1922 to 1991. It was a successor state to the Russian Empire that was nominally organized as a federal union of fifteen national republics, the largest and most populous of which was the Russian SFSR; in practice both its government and economy were highly centralized until its final years. As a one-party state governed by the Communist Party of the Soviet Union, it was a flagship communist state.
The Soviet Union’s roots lay in the October Revolution of 1917, which saw the Bolsheviks overthrow the Russian Provisional Government that formed earlier that year following the February Revolution that had dissolved the Russian Empire. The new government, led by Vladimir Lenin, established the Russian Soviet Federative Socialist Republic (RSFSR), the world’s first constitutionally socialist state. The revolution was not accepted by all within the Russian Republic, resulting in the Russian Civil War between the Bolsheviks and the anti-communist Whites. As the war progressed in the Bolsheviks’ favor, the RSFSR began to incorporate land acquired from the war into various puppet states, which were merged into the Soviet Union in December 1922. Following Lenin’s death in 1924, Joseph Stalin came to power, inaugurating a period of rapid industrialization and forced collectivization that led to significant economic growth, but also contributed to a famine in 1930 to 1933 that killed millions. The forced labour camp system of the Gulag was also expanded in this period. During the late 1930s, Stalin conducted the Great Purge to remove actual and perceived opponents, resulting in mass death, imprisonment, and deportation. In 1939, the USSR and Nazi Germany signed a nonaggression pact despite their ideological incongruence; nonetheless, in 1941, Nazi Germany invaded the Soviet Union in the largest land invasion in history, opening the Eastern Front of World War II. The Soviets played a decisive role in defeating the Axis powers in 1945, suffering an estimated 27 million casualties, which accounted for the majority of Allied losses. In the aftermath of the war, the Soviet Union consolidated the territory occupied by the Red Army, forming various satellite states, and undertook rapid economic development which cemented its status as a superpower.
Following World War II, ideological tensions with the United States eventually led to the Cold War. The American-led Western Bloc coalesced into NATO in 1949, prompting the Soviet Union to form its own military alliance, commonly known as the Warsaw Pact, in 1955. Neither side ever engaged in direct military confrontation, and instead fought on an ideological basis and through proxy wars. In 1953, following Stalin’s death, the Soviet Union undertook a campaign of de-Stalinization under the leadership of Nikita Khrushchev, which saw reversals and rejections of Stalinist policies. This campaign caused tensions with Communist China. During the 1950s, the Soviet Union rapidly expanded its efforts in space exploration and took an early lead in the Space Race with the first artificial satellite, the first human spaceflight, the first space station, and the first probe to land on another planet (Venus). The Cuban Missile Crisis of October 1962 was the closest the Cold War came to escalating into full-scale nuclear war.
The 1970s saw a brief détente in the Soviet Union’s relationship with the United States, but tensions emerged again following the Soviet invasion of Afghanistan in 1979. From 1985, the last Soviet leader, Mikhail Gorbachev, sought to reform the country through his policies of glasnost and perestroika. In 1989, various countries of the Warsaw Pact overthrew their Soviet-backed regimes, and nationalist and separatist movements erupted across the entire Soviet Union. In 1991, amid efforts to reform and preserve the country as a renewed federation, an attempted coup d’état against Gorbachev by hardline communists prompted the three most populous and economically developed republics—Ukraine, Russia, and Belarus—to secede from the Union. On December 26, Gorbachev officially recognized the dissolution of the Soviet Union. Boris Yeltsin, the leader of the RSFSR, oversaw its reconstitution into the Russian Federation, which became the Soviet Union’s successor state; all other republics emerged as fully independent post-Soviet states.
During its existence, the Soviet Union produced many significant social and technological achievements and innovations. It had the world’s second-largest economy and largest standing military. An NPT-designated state, it wielded the largest arsenal of nuclear weapons in the world. As an Allied nation, it was a founding member of the United Nations as well as one of the five permanent members of the United Nations Security Council. Before its dissolution, the USSR was one of the world’s two superpowers through its hegemony in Eastern Europe, global diplomatic and ideological influence (particularly in the Global South), military and economic strengths, and scientific accomplishments.