What was World War II?

World War II was a war that took place between 1939 and 1945 . He faced two large blocks:

  • The Axis : made up of Nazi Germany, Fascist Italy and Japan. Later Hungary, Romania and Bulgaria joined, among others. Its main leaders were Adolf Hitler, Benito Mussolini and the Japanese Emperor Hirohito.
  • Allies : initially formed by Poland, France and Great Britain. China, the Soviet Union and the United States of America, among others, joined later. Its main leaders were the English Winston Churchill, the Soviet Joseph Stalin, the American Franklin Delano Roosevelt and the French Charles De Gaulle.

The war involved 23 countries and took place in Europe, Africa, Asia, Oceania, and in the Atlantic and Pacific oceans. It is considered the bloodiest in universal history. It was won by the allies after six years of fighting.

British soldiers landing on Gold Beach, a beach in France, 1944.

Countries that participated

During World War II the greatest world powers participated together with their allies. The various leading countries are listed below:

The axis Allies Germany (Hitler) Soviet Union (Stalin) Japan (Hirohito) United States (Roosevelt) Italy (Mussolini) England (Churchill) Hungary France (De Gaulle) Romania China (Kai-shek) Bulgaria Poland Iraq Iran


The most remote antecedent of the Second World War was the Crimean War (1853-56), during which France, Great Britain and Italy faced Greece and the Russian Empire. The importance of that conflict was that, after many centuries of fighting, the French and the English fought together against a common enemy .

The next precedent was the Franco-Prussian War (1870-71), during which the German Empire defeated the Second French Empire and took Alsace and Lorraine from it. The loss of those provinces rich in forest and mineral resources was a severe blow to the French and generated resentment against the Germans . This resentment, together with other issues (colonial expansion, spread of nationalist ideas, etc.), was one of the causes of the outbreak of the First World War, in 1914.

During that conflict, France, supported by the Russian Empire and Great Britain (and from 1917 by the United States) defeated the German Empire and recovered Alsace and Lorraine.

The German defeat left a deep mark among groups of veterans , including former Austrian corporal Adolf Hitler . These men spread the idea that the defeat was due to an alleged betrayal (the backstab theory) orchestrated by leaders of Jewish origin .

The harsh conditions imposed on Germany by the Treaty of Versailles increased resentment towards the French, whose prime minister, Georges Clemenceau, insisted on inflicting an exemplary punishment on the Germans.

The Great Depression caused an economic crisis in the Weimar Republic and led to the victory of the Nazi Party in the 1933 elections . With the powers conferred on him by the office of chancellor, in a short time Hitler ended the parliamentary republic and replaced it with a dictatorship. That authoritarian regime proclaimed the right to recover the territories lost during the Great War (including Alsace and Lorraine) and unite all German-speaking countries in a Greater Germany that spanned central and eastern Europe.

The annexation of Austria and Czechoslovakia, both in 1938, were the immediate antecedents of the Second World War , due to a passive attitude of the British and some French leaders, who believed that in this way they would avoid the start of warlike actions.


It began on September 1, 1939 when Germany invaded Poland. Since this country had a defensive alliance with France and Great Britain, these two states declared war on Germany. Around the same time, the Soviet Union invaded Latvia, Lithuania, Estonia, Finland, and eastern Poland.

During the 1940s, Germany occupied Denmark, Norway, Belgium, the Netherlands, and France. In parallel, Italy invaded Albania and Greece, but suffered several defeats. For that reason, Hitler decided to invade the Balkan Peninsula and occupy Yugoslavia, Albania and Greece.

In 1941, the war took a dramatic turn , as Germany invaded the Soviet Union. Shortly after, the attack on Pearl Harbor occurred: Japan launched a surprise air strike against a US military base in Hawaii. From then on, the United States and the Soviet Union allied themselves with Great Britain, which alone resisted the attacks of German aviation.

During 1942, the Axis forces continued to conquer territories, but after 1943 they began to retreat. That year, Mussolini was replaced by a new government that broke the alliance with Hitler. Meanwhile, the Soviet Union, after halting the German advance at the Battle of Stalingrad, began to retake territories it had lost. Japan, for its part, suffered several defeats at the hands of the United States.

During 1944 the allies carried out the Normandy landings in France. Before long Paris was liberated and the allies attacked the German borders.

The war in Europe came to an end in May 1945 , when the Allied forces occupied Berlin and achieved the surrender of Germany, after Hitler’s suicide. In the East, the war ended in September , after the United States dropped atomic bombs on the Japanese cities of Hiroshima and Nagasaki.


Among the multiple causes of World War II, the following stand out:

  • The discontent of the Germans with the conditions imposed by the Treaty of Versailles, after the end of the First World War. Germany then lost a seventh of its territory, was forced to pay war reparations, had its army reduced, and was forbidden to make weapons.
  • The ambitions of Hitler , who sought to recover the territories lost in 1919 and conquer a “living space” that would ensure the development of Germany as the leading world power.
  • The hesitant attitude of the League of Nations, which did not know how to react to the German rearmament, the annexation of Austria and the German occupation of Czechoslovakia, both in 1938.
  • The claims of Mussolini , who wanted to create an Italian Empire like the old Roman Empire.
  • Japanese militarism , which resulted in the annexation of Korea (1910), the occupation of Manchuria (1931), and the invasion of China (1937).
  • The ambitions of Stalin , who wanted to recover the territories that Russia had lost in 1918. Those ambitions led him to sign a non-aggression pact with Hitler that sealed the fate of the Baltic countries. The invasion of Poland by Germany, more than cause, was the trigger, the spark that triggered the conflict.


The Second World War had political, territorial, economic, demographic and social consequences.

Political fallout

The political consequences of World War II were:

  • The end of totalitarian regimes in Germany, Italy and Japan and their replacement by more democratic political systems.
  • The emergence of the United States and the Soviet Union as world superpowers . The different political, social and economic systems of these countries led to the beginning of a competition for world supremacy known as the Cold War. Due to these ideological differences, the world was divided into two opposing political blocs: the communist and the capitalist .
  • The beginning of a decolonization process motivated, among other reasons, by the aid provided by the colonies to their metropolises during the war. This process led to the independence of a large number of countries in Asia and Africa in a few years .
  • The creation in 1945 of the United Nations Organization (UN), which replaced the League of Nations.

Economic consequences

The economic consequences of World War II were:

  • A large number of cities, ports, bridges, roads and railways were destroyed due to land and air bombardments, which seriously affected the economy of the belligerent countries.
  • The United States and the Soviet Union created a large arms industry , which continues today.
  • The United States implemented the Marshall Plan to give financial support to war-torn European countries. The objective of that aid was not only economic; it was also motivated by fear of the spread of communism in Western Europe.
  • Institutions, such as the World Bank and the International Monetary Fund , were created to deal with global financial crises.

Demographic and social consequences

The demographic and social consequences of World War II were:

  • The death of some 60 million people , between military and civilians. Among them, the millions of Jews, gypsies, homosexuals, the disabled and opponents who were murdered in the concentration and extermination camps of Nazi Germany. The Jewish Holocaust was one of the cruelest and bloodiest genocides in world history.
  • After the war, another hundreds of thousands of people died of starvation and various diseases . In Japan, thousands of people died after 1945, affected by radiation from the bombs dropped by the United States on Hiroshima and Nagasaki.
  • There were intense migratory movements , both of people displaced by the war seeking to return to their homes, and of Europeans who settled in America or who returned to Europe when the struggles for decolonization began in Asia and Africa.

Territorial consequences

The territorial consequences of World War II were:

  • Germany lost a large part of its territory , which was divided between Austria, France, Belgium, the Netherlands, Poland and Czechoslovakia. In addition, it was occupied by troops from the United States, the Soviet Union, France and Great Britain.
  • Italy lost all its colonies in Africa and small territories that were given to France, Yugoslavia and Greece.
  • Japan lost all of its colonies and was occupied by US troops.
  • The Soviet Union enlarged its territory with the addition of Estonia, Latvia, Lithuania, and parts of Poland, Finland, and Romania.
  • The United States incorporated several Pacific archipelagos , such as Wake and Guam, among others.

Most important battles

The most notable armed conflicts that occurred during World War II are listed below:

Name Date Belligerents Result Invasion of Poland 1939 Germany vs. Poland German victory. London Blitz 1940 United Kingdom vs. Germany German defeat. Attack on Pearl Harbor 1941 United States vs. Japan Japanese victory. Battle of El Alamein 1942 Allies vs. the Axis allied victory. Battle of Stalingrad 1942 Germany vs. Soviet Union Soviet victory. Battle of Kursk 1943 Germany vs. Soviet Union Soviet victory. Battle of Normandy 1944 Allies vs. Germany Allied victory. Battle of the Bulge 1944 Allies vs. Germany Allied victory. Liberation of Paris 1944 Allies vs. Germany Allied victory. Battle of Berlin 1945 Germany vs. Soviet Union Soviet victory.

End of the war

In 1945 the war ended thanks to the fact that the American troops and the Russian troops managed to make contact with the German regime and divide it into parts, forcing it to return all the territory it had conquered.

It was then that Germany signed an agreement in which it surrendered and abandoned its aims of conquest , which put an end to the world war in Europe.

A different situation happened with Japan, since this country did not want to bow down to its enemies. In this way, the United States carried out the first nuclear bombardment on the city of Hiroshima , causing its complete destruction.

Then, just 3 days after the nuclear event, another bomb was dropped on Nagasaki, causing Japan, on September 2, 1945, to surrender and end World War II.

Frequent questions

Who won World War II?

World War II was won by the Allies .

When did World War II start?

The war began on Friday, September 1, 1939, when Germany invaded Poland.

When did World War II end?

The war ended on Sunday, September 2, 1945 , when Japan surrendered after another bomb was dropped on Nagasaki.

What countries participated in World War II?

Among the main countries that participated are: Germany, Japan, Italy, Hungary, Romania, Bulgaria, Iraq, Iran on the side of The axis . Soviet Union, United States, England, France, China and Poland on the side of the Allies .

How long did World War II last?

The war took place between Friday, September 1, 1939, and September 2, 1945 (2,193 days) .

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