World War II

Between September 1939 and August 1945, approximately 70 to 85 million people died in the most destructive conflict in human history—roughly 3% of the world’s population. The war was fought across every ocean and on every inhabited continent. It destroyed the European state system that had dominated global politics for four centuries, replaced it with a bipolar order dominated by the United States and the Soviet Union, and produced the nuclear weapon—a technology capable of ending civilization itself. The United Nations, NATO, the Bretton Woods institutions, the European Union, the state of Israel, the division of Korea, the Chinese Communist revolution, and the Decolonization of Asia and Africa all flowed directly from this single catastrophe.

Understanding World War II is not merely a matter of historical interest. The international order we inhabit—its institutions, its norms, its distribution of power, its unresolved conflicts—was forged in the fire of 1939-1945. The war’s lessons, real and perceived, continue to shape how leaders think about deterrence, appeasement, alliance, and the use of force. When policymakers invoke “Munich” to argue against concession or cite the costs of total war to counsel restraint, they are drawing on a conflict whose shadow stretches across every subsequent decade.

Origins¶

The Failure of Versailles¶

World War II’s origins lie in the settlement that ended World War I. The Treaty of Versailles (1919) imposed punishing terms on Germany—territorial losses, military restrictions, and reparations equivalent to approximately $33 billion (roughly $500 billion in current value). The treaty was harsh enough to humiliate Germany but not harsh enough to permanently weaken it. France wanted Germany dismembered; Britain wanted a European balance; the United States retreated into isolationism. The result satisfied no one.

The Weimar Republic that governed Germany from 1919 to 1933 was born under the stigma of defeat and the burden of Versailles. Hyperinflation in 1923 wiped out the savings of the middle class. The Great Depression after 1929 pushed unemployment above 30%. In this atmosphere of desperation and resentment, Adolf Hitler’s National Socialist Party rose from the political fringe to government. Hitler became chancellor in January 1933 and established a totalitarian dictatorship within months.

The Collapse of the International Order¶

The 1930s witnessed the systematic destruction of the post-World War I order:

Japanese aggression: Japan invaded Manchuria in 1931 and withdrew from the League of Nations when condemned. Full-scale invasion of China followed in 1937, producing atrocities including the Nanjing Massacre (approximately 200,000-300,000 killed).
Italian expansionism: Mussolini’s Italy invaded Ethiopia in 1935. The League of Nations imposed Sanctions but could not enforce them. The failure destroyed the League’s credibility.
German rearmament and expansion: Hitler withdrew from the League (1933), reintroduced conscription (1935), remilitarized the Rhineland (1936), annexed Austria (March 1938), and demanded the Sudetenland from Czechoslovakia.
The Munich Agreement (September 1938): Britain and France agreed to Hitler’s demands, ceding the Sudetenland in exchange for a promise of “peace for our time.” Six months later, Hitler occupied the rest of Czechoslovakia, proving that appeasement had failed.

The Nazi-Soviet Pact¶

On August 23, 1939, the world’s two most antagonistic ideologies signed a non-aggression pact. The Molotov-Ribbentrop Agreement between Nazi Germany and the Soviet Union included secret protocols dividing Eastern Europe into spheres of influence. Poland would be partitioned; the Baltic states, Finland, and Bessarabia fell into the Soviet sphere.

The pact freed Hitler to invade Poland without facing a two-front war. It gave Stalin time and territory—a buffer zone he believed essential for Soviet security. It also represented a catastrophic miscalculation by both dictators: Hitler assumed the Western powers would again accept a fait accompli; Stalin assumed he had years to prepare for an eventual German attack. Both were wrong.

On September 1, 1939, Germany invaded Poland. Britain and France declared war on September 3. World War II had begun.

The War in Europe¶

Blitzkrieg and Conquest (1939-1941)¶

Germany’s early campaigns demonstrated a revolutionary approach to warfare. Blitzkrieg—“lightning war”—combined concentrated armor, mechanized infantry, close air support, and radio communication to achieve breakthroughs at unprecedented speed:

Poland fell in five weeks (September-October 1939). The Soviet Union invaded from the east on September 17, completing the partition.
Denmark and Norway fell in April 1940, securing Germany’s northern flank and access to Swedish iron ore.
France, the continent’s premier military power, collapsed in six weeks (May-June 1940). The Wehrmacht bypassed the Maginot Line through the Ardennes Forest, encircled the Allied armies, and forced France’s surrender on June 22. The fall of France was the greatest military shock of the century—a nation of 40 million with Europe’s largest army defeated in weeks.
The Battle of Britain (July-October 1940): Hitler’s attempt to achieve air superiority over Britain as a precondition for invasion failed. The Royal Air Force, aided by radar and Ultra codebreaking intelligence, inflicted unsustainable losses on the Luftwaffe. Britain survived alone.

By mid-1941, Nazi Germany controlled or allied with virtually all of continental Europe—from the Atlantic to the Soviet border, from Norway to North Africa.

Operation Barbarossa and the Eastern Front¶

On June 22, 1941, Germany launched the largest military operation in history. Operation Barbarossa sent 3.8 million troops, 3,600 tanks, and 2,700 aircraft across a 2,900-kilometer front into the Soviet Union. Hitler’s objectives were the destruction of the Red Army, the seizure of Soviet resources (Ukrainian grain, Caucasus oil, Ural minerals), and the creation of Lebensraum—living space for German settlers in the east.

The Eastern Front became the war’s decisive theater. The scale was staggering: at its peak, the front stretched 2,900 kilometers from Leningrad to the Black Sea. Approximately 80% of German military casualties occurred on the Eastern Front. The Soviet Union lost an estimated 27 million people—more than half of all World War II deaths—including approximately 8.7 million military dead and 19 million civilians.

Key turning points on the Eastern Front:

The Battle of Moscow (October 1941-January 1942): The Wehrmacht reached within 30 kilometers of the Soviet capital before a Soviet counteroffensive, aided by the Russian winter and fresh Siberian divisions, pushed it back.
The Battle of Stalingrad (August 1942-February 1943): The war’s most decisive battle. The German Sixth Army, attempting to capture the city on the Volga, was encircled and destroyed. Of approximately 300,000 German troops trapped, only 91,000 survived to surrender; fewer than 6,000 ever returned home. Stalingrad broke the myth of German invincibility.
The Battle of Kursk (July 1943): The largest tank battle in history involved approximately 6,000 tanks and 2 million troops. The Soviet victory ended Germany’s capacity for strategic offensive on the Eastern Front.

After Kursk, the Red Army advanced relentlessly westward, liberating Soviet territory, then pressing through Poland, Romania, Hungary, and into Germany itself. Berlin fell on May 2, 1945. Hitler had committed suicide two days earlier.

The Western Front and Allied Victory¶

The Western Allies opened a second front with the D-Day invasion of Normandy on June 6, 1944—the largest amphibious operation in history. Approximately 156,000 troops crossed the English Channel on the first day, supported by 5,000 ships and 11,000 aircraft. The beachheads held, and within weeks the Allies had landed over a million men in France.

The liberation of France, the crossing of the Rhine (March 1945), and the link-up with Soviet forces on the Elbe (April 1945) brought the European war to its conclusion. Germany surrendered unconditionally on May 8, 1945—V-E Day.

The War in the Pacific¶

Japanese Expansion¶

Japan’s attack on Pearl Harbor on December 7, 1941, brought the United States into the war and transformed a European conflict into a truly global one. Within six months, Japan conquered the Philippines, Malaya, Singapore, the Dutch East Indies, Burma, and dozens of Pacific Islands—an empire stretching from the borders of India to the mid-Pacific.

The Japanese occupation was brutal. Forced labor, mass executions, and systematic exploitation characterized the “Greater East Asia Co-Prosperity Sphere.” The fall of Singapore in February 1942—where 80,000 British and Commonwealth troops surrendered to a smaller Japanese force—shattered the myth of European invincibility in Asia and accelerated the eventual Decolonization of the continent.

Island-Hopping and Attrition¶

The American strategy of island-hopping—bypassing heavily fortified Japanese positions while seizing strategically vital islands—gradually pushed the perimeter of Japanese control back toward the home islands:

Midway (June 1942): The war’s naval turning point. American codebreakers identified the Japanese target, enabling an ambush that sank four Japanese aircraft carriers. Japan never recovered its offensive naval capability.
Guadalcanal (August 1942-February 1943): Six months of brutal jungle fighting established the pattern of attritional warfare that characterized the Pacific campaign.
Iwo Jima and Okinawa (1945): The final island campaigns produced ferocious Japanese resistance—at Okinawa, approximately 100,000 Japanese troops and 100,000 civilians died—foreshadowing the expected cost of invading Japan proper.

The Atomic Bomb¶

On August 6, 1945, an American B-29 bomber dropped an atomic bomb on Hiroshima, killing approximately 80,000 people instantly and perhaps 140,000 by year’s end. A second bomb struck Nagasaki on August 9, killing approximately 40,000 immediately. Japan surrendered on August 15, 1945.

The decision to use nuclear weapons remains the most debated in military history. Proponents argue it prevented an invasion of Japan that military planners estimated would cost 250,000-1,000,000 Allied casualties and far more Japanese deaths. Critics note that Japan was already seeking surrender terms and that the bombs’ primary purpose was to demonstrate power to the Soviet Union—the opening act of the Cold War rather than the closing act of World War II.

Whatever the justification, the atomic bomb transformed international politics permanently. The nuclear age had begun, and with it the possibility that great power war could end civilization itself.

The Holocaust¶

The Nazi regime’s systematic murder of approximately six million Jews—along with millions of Roma, disabled persons, political dissidents, prisoners of war, and others—represents an atrocity without precedent. The Holocaust was not a byproduct of war but a central objective of the Nazi state, pursued with industrial efficiency even as it diverted resources from the military effort.

The extermination camps—Auschwitz, Treblinka, Sobibor, Belzec, Chelmno, Majdanek—operated as factories of death. At Auschwitz-Birkenau alone, approximately 1.1 million people were murdered, most in gas chambers. The Einsatzgruppen—mobile killing units—shot approximately 1.5 million Jews in occupied Soviet territory.

The Holocaust’s geopolitical legacy extends beyond the moral catastrophe itself. It generated the political will for the creation of the state of Israel in 1948—a decision whose consequences continue to shape the Middle East. It provided the moral foundation for the Universal Declaration of Human Rights (1948) and the Genocide Convention. And it demonstrated what modern states are capable of when ideology overcomes restraint—a warning that retains its force.

Geopolitical Consequences¶

The Birth of the Superpower Era¶

World War II destroyed the multipolar European order that had dominated global politics since the Congress of Vienna. In its place emerged a bipolar system dominated by two superpowers:

The United States emerged with its homeland untouched, its economy producing half of global GDP, its military possessing nuclear weapons, and its navy controlling every ocean. American war production had been staggering: 297,000 aircraft, 86,000 tanks, 2.7 million machine guns, 6,500 naval vessels. No nation in history had possessed such overwhelming material superiority.

The Soviet Union emerged devastated but victorious. Despite losing 27 million people and having its western territory laid waste, the Red Army occupied half of Europe. Soviet prestige was immense—it was Soviet forces that had broken the Wehrmacht’s back, and Soviet sacrifices that had made victory possible. Moscow’s control of Eastern Europe gave it a strategic position in the heart of the continent.

The traditional European great powers were spent. Britain was bankrupt, its empire crumbling. France was traumatized by defeat and occupation. Germany was destroyed and divided. Japan lay in ruins under American occupation. The era of European dominance, stretching back to the Age of Exploration, was over.

The Institutional Order¶

The war’s victors created institutions designed to prevent a recurrence of the catastrophe:

The United Nations (1945): Unlike the failed League of Nations, the UN included both superpowers. The Security Council, with its five permanent members wielding vetoes, enshrined great power privilege while providing a forum for collective action.
The Bretton Woods System (1944): The International Monetary Fund and World Bank established rules for international finance. The dollar, pegged to gold, became the world’s reserve currency. This system provided the monetary stability that enabled postwar economic recovery.
The General Agreement on Tariffs and Trade (1947): The precursor to the WTO promoted trade liberalization, reversing the protectionist spiral of the 1930s that had deepened the Depression and accelerated the march toward war.
NATO (1949): The North Atlantic Treaty Organization committed the United States to European defense—the first peacetime military alliance in American history. NATO’s creation institutionalized the American security guarantee that made European integration possible.

These institutions, designed in the shadow of total war, still govern international relations eight decades later.

Decolonization¶

The war fatally undermined European colonialism. Japan’s conquests in Asia had shattered the myth of European military supremacy. Millions of colonial subjects had fought for imperial powers that promised them nothing in return. The Atlantic Charter (1941), in which Roosevelt and Churchill declared support for self-determination, provided rhetorical ammunition for independence movements.

The result was a wave of Decolonization that created over 100 new states between 1945 and 1975. India and Pakistan (1947), Indonesia (1949), Indochina (1954), much of Africa (1960s)—the colonial empires dissolved in a generation. This transformation created the “Third World” that became the primary arena of Cold War competition and remains the source of many contemporary conflicts.

The Division of Europe and Asia¶

The war’s end left Europe and Asia divided along lines that persisted for decades:

Germany was split into four occupation zones, then consolidated into West Germany (aligned with the United States) and East Germany (controlled by the Soviet Union). Berlin, deep within the Soviet zone, was similarly divided. The division lasted until 1990.
Korea was divided at the 38th parallel between Soviet and American occupation zones. The division persists to this day, making the Korean Peninsula the Cold War’s most dangerous frozen conflict.
Eastern Europe fell under Soviet control. Poland, Czechoslovakia, Hungary, Romania, Bulgaria, and Albania became communist states within the Soviet sphere. Their subjugation defined the Cold War’s central fault line.

The Nuclear Revolution¶

Hiroshima and Nagasaki inaugurated a revolution in international politics. For the first time in history, great powers possessed weapons capable of destroying each other’s societies entirely. This reality—what theorists call the condition of mutual assured destruction—fundamentally altered the logic of great power competition.

Nuclear weapons made direct war between major powers potentially suicidal. The Cold War that followed was “cold” precisely because nuclear weapons made it “hot” war unthinkable. Deterrence replaced defense as the organizing principle of security policy. The paradox was profound: weapons too terrible to use became essential to possess, and security came to depend on the credible threat of civilizational destruction.

The spread of nuclear weapons beyond the original five powers—and the ongoing danger of further proliferation—remains one of the war’s most consequential legacies.

Lessons and Legacies¶

Appeasement and Its Shadow¶

Munich became the most powerful analogy in postwar diplomacy. The lesson drawn—that dictators must be confronted early, before they grow strong enough to be unstoppable—shaped decisions from Korea to Kosovo. American policymakers invoked Munich to justify intervention in Vietnam, the Gulf War, and Iraq. The analogy’s power has sometimes exceeded its applicability: not every adversary is Hitler, and not every concession is Munich. But the appeasement lesson remains deeply embedded in Western strategic culture.

The Primacy of American Power¶

American participation proved decisive—as it had in World War I. The lesson that American engagement in the international system was essential to global stability replaced the isolationism that had characterized American foreign policy before 1941. The post-1945 American commitment to European and Asian security, maintained through NATO and bilateral alliances, represented a permanent departure from the prewar norm. Whether that commitment will endure in the face of rising powers and domestic pressures is among the central questions of contemporary geopolitics.

Total War and Its Limits¶

The sheer destruction of World War II—entire cities obliterated, civilian populations deliberately targeted, industrial societies mobilized for annihilation—produced a revulsion against major war that has shaped international behavior ever since. The norm against great power war, reinforced by nuclear weapons, has held since 1945—the longest such period in modern history. Whether this norm will survive the return of Great Power Competition between the United States, China, and Russia is the defining question of the 21st century.

Sources & Further Reading¶

The Second World War by Antony Beevor — The most comprehensive single-volume military history, combining strategic analysis with vivid narrative across every theater of the war.
The Rise and Fall of the Third Reich by William L. Shirer — A journalist’s panoramic account of Nazi Germany from its origins through its destruction, drawing on personal experience and captured German documents.
Wages of Destruction: The Making and Breaking of the Nazi Economy by Adam Tooze — Groundbreaking economic history demonstrating how resource constraints shaped German strategy and how the war’s outcome was determined as much by industrial capacity as by battlefield tactics.
Inferno: The World at War, 1939-1945 by Max Hastings — A global history emphasizing the human experience of war, from the Eastern Front to the Pacific, with particular attention to the conflict’s moral complexities.
Diplomacy by Henry Kissinger — The chapters on the interwar period and World War II’s origins offer a master strategist’s analysis of how the failure of the Balance of Power produced catastrophe.