The Grand Alliance Breaks Apart (1943-1947)

During World War II, Britain, the USA, and USSR were unlikely allies fighting Hitler - but their friendship didn't last long after victory. At three major conferences, the cracks started showing as Stalin, Churchill, and Roosevelt (later Truman) tried to carve up post-war Europe.

The Tehran Conference (1943) seemed promising - everyone agreed to defeat Germany and set up the United Nations. But by Yalta (1945), tensions were rising over Poland's future, even though they agreed to split Germany into four zones.

Potsdam (1945) was where things properly fell apart. Truman had replaced Roosevelt and wasn't keen on Stalin's plans for Eastern Europe. The USA's secret atomic bombs dropped on Japan made Stalin incredibly suspicious - suddenly America had a terrifying weapon that could end civilisations.

Key Point: The alliance that defeated Hitler crumbled because capitalism and communism were fundamentally incompatible ideologies - like oil and water, they just couldn't mix.

Two superpowers emerged from the war's ashes, each convinced the other wanted to destroy their way of life. Stalin created satellite states across Eastern Europe as a buffer zone, while America watched nervously as the "Iron Curtain" fell across the continent. The Truman Doctrine and Marshall Plan were America's attempts to contain communism, whilst Stalin hit back with Cominform and Comecon.

Berlin Crisis and the Arms Race (1948-1956)

When the Western allies merged their German zones into one economic unit, Stalin felt threatened - capitalists were literally on his doorstep. His solution? The Berlin Blockade of 1948, cutting off all road, rail, and canal links to starve West Berlin into submission.

The West's response was brilliant: the Berlin Airlift. For nearly a year, planes flew 8,000 tonnes of supplies daily into the city. New airports were built, and it became clear the West wouldn't back down. Stalin eventually lifted the blockade, but Germany was now permanently split into two rival states.

This crisis sparked the creation of NATO in 1949 - a military alliance where an attack on one meant war with all. The USSR responded with the Warsaw Pact, creating two armed camps across Europe.

Key Point: The arms race began in earnest as both sides stockpiled nuclear weapons, terrified of falling behind in the ultimate game of one-upmanship.

From atom bombs to hydrogen bombs to intercontinental missiles, each side matched the other's advances. The competition even spilled into space - if you could launch satellites, you could launch nuclear warheads anywhere on Earth. Khrushchev, Stalin's successor, wanted "peaceful co-existence" but was equally determined to prove communism's superiority.

The Hungarian Uprising (1956) showed the limits of this new relationship. When Hungarians tried to leave the Warsaw Pact, Soviet tanks rolled in, killing thousands and executing their leader Nagy. The message was clear: satellite states weren't free to choose their own path.

Berlin Wall and Cuban Revolution (1958-1961)

By the late 1950s, West Berlin had become an embarrassing problem for the USSR. Whilst East Berlin stagnated under communist rule, the western half thrived economically. Over 3 million East Germans had fled to the West by 1961 - a brain drain that made communism look like a complete failure.

Khrushchev's ultimatum in 1958 demanded Western troops leave Berlin within six months, but nothing came of it. The Paris Summit collapsed spectacularly when the Soviets shot down an American spy plane, and Eisenhower refused to apologise.

When JFK became president, he took an even tougher stance. The Vienna Summit achieved nothing, leaving Khrushchev convinced the young president was weak.

Key Point: The Berlin Wall, built overnight in 1961, became the ultimate symbol of communist oppression - a concrete barrier topped with barbed wire where guards shot anyone trying to escape.

Meanwhile, revolution was brewing in Cuba. Fidel Castro overthrew the unpopular dictator, worrying America as they had massive economic interests there. When the USA threatened to stop buying Cuban sugar, Castro signed deals with the USSR instead.

The Bay of Pigs invasion (1961) was a disaster - Kennedy's attempt to overthrow Castro using Cuban rebels failed miserably. America was humiliated, and Cuba was pushed firmly into the Soviet camp. Castro announced Cuba was officially communist, bringing the Cold War right to America's doorstep.

Cuban Missile Crisis and Prague Spring (1962-1970)

October 1962 brought the world closer to nuclear war than ever before or since. Khrushchev decided to place nuclear missiles in Cuba, giving him the ability to strike American cities with virtually no warning. When American spy planes spotted the missile bases under construction, Kennedy was furious.

The president demanded the missiles be removed and ordered a naval blockade of Cuba - all Soviet ships would be stopped and searched. For thirteen terrifying days, the world held its breath as the two superpowers faced off.

Khrushchev eventually backed down, agreeing to remove the missiles in exchange for America's promise not to invade Cuba (and secretly removing missiles from Turkey). Kennedy looked like a hero, whilst Khrushchev appeared weak - contributing to his downfall.

Key Point: The crisis led to practical steps to prevent future disasters: a hotline between Washington and Moscow, and treaties banning nuclear tests and weapons in space.

The Prague Spring (1968) showed the Cold War was far from over. When Dubček tried to give Czechoslovakia more freedom and closer ties with the West, Brezhnev wasn't having it. 500,000 Soviet troops invaded, crushing the reforms with overwhelming force.

The Brezhnev Doctrine made it crystal clear: any threat to communism in Eastern Europe would be met with Soviet tanks. This sent shockwaves through the communist world and proved that despite talks of peaceful co-existence, the USSR would use military force to maintain control over its satellite states.