The Cold War was the ideological, economic, and military struggle between the geopolitical camps headed by the United States and the Soviet Union (USSR), respectively, which lasted from the end of World War II in 1945 until the dissolution of the Soviet Union and the end of Communist rule in Eastern Europe in 1989-1991. Uniquely among modern wars, the primary antagonists never engaged in direct, offensive military operations against each other, largely out of fear of a nuclear exchange that could destroy both sides (and the global environment in a hypothetical worst-case scenario). Instead, the war was fought out in a variety of alternate arenas, including through proxies in the developing world (Korea, Cuba, Vietnam, Afghanistan, etc.), clandestine intelligence operations, and the Space Race. A number of times, there were standoffs between the US and the USSR, the most famous being the Cuban Missile Crisis of 1962 ("Cold War," Encyclopedia Britannica).
On the timeline below, certain names and terms are bolded; these are suggested research topics.
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May 1945: End of World War II in Europe and the division of Germany (and of its capital city, Berlin) into occupation zones corresponding to the four Allied powers: France, the United Kingdom, the United States, and the Soviet Union.
July-August 1945: Potsdam Conference in Germany among the leaders of the US, the UK, and the USSR to determine post-war world order.
August 1945: Atomic bombings of the Japanese cities of Hiroshima and Nagasaki effectively end World War II and introduce the world to the concept of nuclear war.
c. 1945-1948: The Soviet Union communizes the sections of Eastern Europe under its occupation.
February 1946: American diplomat George F. Kennan writes the Long Telegram in response to the inauguration of Stalin's Five-Year Plan; the document influences US Soviet policy for years to come.
March 1946: Winston Churchill delivers his famous Iron Curtain speech in Fulton, Missouri.
June 1948 - May 1949: The Soviets blockade West Berlin in an attempt to starve its populace into submission. The Western allies respond with the Berlin Airlift operation, keeping the city supplied by air until the Soviets back down.
April 1949: Foundation of the North Atlantic Treaty Organization (NATO) by the US, the UK, France, Belgium, The Netherlands, Luxembourg, Italy, Portugal, Denmark, Iceland, Norway, and Canada.
August 1949: The Soviet Union successfully detonates an atomic bomb, becoming the second nuclear power.
October 1949: The Chinese Civil War ends in victory for Mao Zedong and the Communists, who proclaim the People's Republic of China. The defeated Nationalists retreat to Taiwan.
1950: US Senator Joseph McCarthy inaugurates the era of paranoia and persecution of suspected Communists that will come to be associated with his name.
1950-1953: The Korean War. US-led forces repel a North Korean invasion of South Korea, but Chinese intervention prolongs the war, eventually leading to stalemate and an armistice that reestablishes the North-South border at the 38th parallel.
October 1952: The United Kingdom becomes the third nuclear power.
November 1952: The US detonates the first hydrogen (thermonuclear) bomb. The USSR follows suit less than a year later.
March 1953: Death of Soviet leader Josef Stalin.
1954: Public opinion turns against McCarthy; the Senate censures him, and his influence fades. Communist North Vietnam achieves de facto independence from colonial French rule following the conclusion of the First Indochina War; still under French occupation, South Vietnam is viewed as a bulwark against further Communist expansion in Southeast Asia.
1955: West Germany's admittance to NATO leads the Soviets to create the Warsaw Pact, a military alliance of Eastern European states.
July 1955: The Geneva summit between the US and the USSR. President Dwight D. Eisenhower proposes an "open skies" policy of unhindered aerial observation of the two superpowers' military installations by each other, but the Soviets reject the idea.
1956: Stalin's successor, Nikita Khrushchev, condemns his predecessor, "de-Stalinizing" the Communist party. The Soviets, however, crack down on the Hungarians when they seek to cast off the USSR's hegemony and form a more democratic state.
October 1957: The USSR launches the first artificial satellite, Sputnik 1, inaugurating the Space Age and shocking the West with its achievement. It is feared that this will give the Soviets the ability to conduct nuclear attacks from space.
1958-1961: Mao's "Great Leap Forward" policy, aimed at rapid industrialization through the creation of self-sufficient communes, results in a famine that claims 6-7 million Chinese lives. Soviet disgust at this failure contributes to rising tensions between the two largest Communist powers.
1959: Cuba becomes a Communist country under the leadership of Fidel Castro, giving the USSR an important foothold in the Western Hemisphere.
1960: An American U-2 spy plane piloted by Francis Gary Powers is shot down over the USSR, leading to the cancelation of a scheduled US-Soviet summit in Paris.
April 1961: Soviet cosmonaut Yuri Gagarin becomes the first human being to orbit the Earth. The CIA-backed Bay of Pigs invasion of Cuba by anti-Castro Cuban exiles ends in failure.
August 1961: The Soviets and East Germans erect the Berlin Wall, cordoning off West Berlin.
October 1962: The detection of Soviet missile bases in Cuba by US spy planes triggers the Cuban Missile Crisis, a military and diplomatic standoff between the superpowers. The crisis is ultimately resolved by the Soviet agreement to remove the missiles in return for the discreet removal of US missiles in Turkey and a US pledge not to invade Cuba.
August 1963: The US, the UK, and the USSR sign the Test-Ban Treaty, prohibiting the testing of nuclear weapons underwater, in the atmosphere, and in space.
November 1963: Assassination of President John F. Kennedy.
1964: China detonates an atomic bomb. Khrushchev is ousted from power, and is succeeded by Leonid Brezhnev.
August 1964: The Gulf of Tonkin Resolution opens the door for escalated US military involvement in the Vietnam War under the leadership of President Lyndon B. Johnson.
1967: Israel wins a sweeping victory over the surrounding Arab states in the Six-Day War.
1968: Soviet crackdown on pro-democracy reforms in Czechoslovakia ("Prague Spring"). Social and political upheaval in the US as the death toll in Vietnam mounts without any end to the war in sight; Dr. Martin Luther King, Jr., and Senator Robert Kennedy are assassinated.
1969: American Apollo 11 astronauts Neil Armstrong and Buzz Aldrin make the first Moon landing.
1972: Richard Nixon makes the first official visit to Communist China by a US president. Nixon also signs the Strategic Arms Limitation Treaty (SALT) and the Anti-Ballistic Missile (ABM) Treaty with the USSR in Moscow. High point for the policy of détente (easing of tensions between the superpowers) that prevails during the middle stages of the Cold War.
1973: American troops withdraw from Vietnam, which is unified under the North Vietnamese Communist regime within three years. Both East and West Germany are admitted to the United Nations. Yom Kippur War between Israel and an Egypt-led Arab alliance; the Israelis are victorious.
1974: The Watergate scandal leads Nixon to resign from office.
1979: The US and Communist China establish full diplomatic relations. The USSR invades Afghanistan in support of an allied regime. President Jimmy Carter brokers the Camp David peace accords between Egypt and Israel. The Iranian Hostage Crisis begins.
1980: The US leads a boycott of the Moscow Olympic Games in response to the Soviet invasion of Afghanistan.
1980-1988: Iran-Iraq War.
1981: The Iranian Hostage Crisis ends peacefully, having lasted 444 days.
1983: President Ronald Reagan announces the planned development of the Strategic Defense Initiative (SDI) antiballistic missile defense system, heightening tensions with the Soviets. Critics dub the SDI "Star Wars."
1985: Mikhail Gorbachev becomes general secretary of the Soviet Politburo; he initiates a policy of emphasizing economic power over military might, and of developing more open relations with the West.
1986-1987: The US secretly sells arms to Iran and diverts the profits to the anti-Communist Contra guerillas of Nicaragua, the public revelation of which leads to scandal and Congressional investigation of senior Reagan administration officials.
1987: The US and the USSR sign the Intermediate Range Nuclear Forces (INF) Treaty reducing nuclear arsenals.
December 1988: Gorbachev announces a large-scale withdrawal of Soviet military forces from Eastern Europe.
1989: Gorbachev increasingly encourages national self-determination in Eastern Europe, reversing decades of Soviet doctrine.
February 1989: Soviet forces withdraw from Afghanistan.
May 1989: Hungary partially opens its border with Austria, creating a breach in the Iron Curtain. Tens of thousands of East Germans flee to the West via this route.
June 1989: The Chinese government crushes a pro-democracy movement in the Tiananmen Square massacre.
November 1989: The East German government grants exit visas to all citizens wishing to visit the West. The Berlin Wall comes down, symbolically ending the Cold War.
December 1989: Free elections in Czechoslovakia. Violent overthrow of Communist dictator Nicolae Ceausescu in Romania.
October 1990: East and West Germany are formally reunified.
June 1991: Boris Yeltsin is elected president of the Russian Republic.
August 1991: Yeltsin leads resistance to a coup by Soviet hard-liners that effectively removes Gorbachev from power. Estonia, Latvia, Ukraine, Belarus, and Moldova declare their independence.
December 1991: Gorbachev resigns, and the USSR is formally dissolved.
("Cold War," "International Relations," Encyclopedia Britannica)