Defeat of Nazi Germany and Imperial Japan

The final phase of World War II was a brutal testament to humanity’s capacity for both destruction and resilience. By early 1945, Allied forces had cracked open the German front, pushing through the heart of Nazi Germany. The Soviet Red Army surged toward Berlin while American and British forces liberated Western Europe town by town.

Inside Germany, morale crumbled and resistance became desperate. Adolf Hitler, once a symbol of unstoppable fascist aggression, was now isolated in his Berlin bunker. In April 1945, Soviet troops stormed the capital in ferocious urban warfare. Hitler’s suicide on April 30 signaled the regime’s collapse, and on May 7, Germany signed an unconditional surrender.

Meanwhile, across the vast Pacific, the United States intensified its campaign against Imperial Japan. Fierce battles like Iwo Jima and Okinawa foreshadowed the staggering losses expected if the Allies invaded Japan’s home islands. Seeking an alternative, President Harry S. Truman authorized the use of a new and devastating weapon: the atomic bomb.

On August 6 and 9, 1945, the cities of Hiroshima and Nagasaki were obliterated. Combined with the Soviet Union’s declaration of war and invasion of Manchuria, these forced Japan’s surrender. On September 2, the formal surrender was signed aboard the USS Missouri in Tokyo Bay.

The end of WWII left the United States and the Soviet Union as global superpowers — rivals whose uneasy alliance was already fraying as the world’s new ideological battle lines were drawn.

Founding of the United Nations

Determined to prevent another global catastrophe after WWII, world leaders created the United Nations (UN). In April 1945, representatives from 50 countries met in San Francisco to draft the UN Charter. When ratified that October, the UN formally replaced the failed League of Nations.

The UN Charter set ambitious goals: maintain peace, protect human rights, and promote social and economic progress. The UN’s headquarters in New York City symbolized this new era of diplomacy and collective security.

Central to this vision was the Security Council, with five permanent members — the US, USSR, UK, France, and China — each holding veto power. This structure aimed to keep major powers engaged and prevent another breakdown like before WWII.

In its early years, the UN oversaw post-war reconstruction and the independence of former colonies. Agencies like WHO and UNICEF addressed health crises and child welfare, becoming trusted symbols of international cooperation.

Despite Cold War tensions paralyzing its political arm at times, the UN remained the world’s principal forum for resolving disputes and coordinating humanitarian efforts, an enduring institution born from WWII’s ashes.

Beginning of US–Soviet Rivalry

The alliance that defeated Hitler quickly fractured as ideological differences resurfaced. The capitalist United States and communist Soviet Union, once united against fascism, now competed to shape the postwar world. Their rivalry defined the Cold War.

Much of the tension centered on the fate of Eastern Europe. Soviet troops occupied countries like Poland and Hungary, installing communist governments. Stalin saw this as essential for security; the West saw it as imperial domination.

In 1946, Winston Churchill’s famous “Iron Curtain” speech warned of Europe divided by ideology and barbed wire. Both sides accused the other of expansionism and subversion.

The US launched the Marshall Plan to rebuild Western Europe and curb communist appeal. Meanwhile, the Soviets tightened control over their bloc, crushing dissent and consolidating power through secret police and propaganda.

By 1949, the division was clear: two camps, armed with competing visions for humanity, and soon, nuclear weapons. The seeds of global confrontation were sown in Europe’s ruins.

Division of Germany; Iron Curtain Descends

Germany became the Cold War’s ground zero. After the war, the Allies split it into four occupation zones: American, British, French, and Soviet. Berlin, deep in Soviet-controlled East Germany, was also divided — a recipe for future crises.

In the West, zones merged into West Germany (Federal Republic of Germany). The Soviets turned their sector into East Germany (German Democratic Republic), ruled by a communist party loyal to Moscow.

Frictions escalated during the Berlin Blockade (1948–49). The Soviets tried to starve out West Berlin by cutting off roads and rail. In response, the Allies launched the heroic Berlin Airlift, flying in supplies for nearly a year until Stalin backed down.

Elsewhere in Eastern Europe, communist regimes locked their borders, suppressed dissent, and stifled independent thought. Stalin’s grip turned Eastern Europe into a buffer zone against the West — but also a prison for millions behind the Iron Curtain.

The divided Germany became a lasting symbol of Cold War confrontation — a line where two worlds collided daily, setting the stage for decades of spycraft, defections, and standoffs in the heart of Europe.

Start of Nuclear Arms Race

WWII ended with the United States as the world’s only nuclear power. But this monopoly didn’t last. Soviet spies in the Manhattan Project passed atomic secrets to Moscow, and in 1949, the Soviets detonated their first atomic bomb, shocking American policymakers.

The dawn of the nuclear arms race meant unimaginable stakes: both superpowers soon had weapons that could obliterate cities and continents. Research moved quickly from atomic bombs to more powerful hydrogen bombs and intercontinental missiles.

Fear gripped the public. Civil defense drills, fallout shelters, and “duck and cover” drills became fixtures of everyday life. Popular culture filled with apocalyptic imagery and doomsday scenarios.

Strategists developed the doctrine of Mutual Assured Destruction (MAD): if either side struck first, it guaranteed total retaliation and mutual extinction. Ironically, this horror arguably kept the peace by making war unthinkable.

The nuclear rivalry shaped everything that followed, driving technology, espionage, diplomacy, and a profound anxiety that haunted the Cold War generation — an existential shadow cast over every crisis and negotiation to come.