The Second World War, also known as World War II, was a conflict that involved almost every part of the world during the years 1939–1945. The main warring parties were the Axis powers: Germany, Italy, and Japan and the Allies: France, Great Britain, the United States, the Soviet Union, and to a smaller extent, China.

Summary of the WWII
Photo by Museums Victoria on Unsplash

The war was in many aspects a continuation of the conflicts left unsettled by World War I, following an unpleasant 20-year absence. The 40 to 60 million deaths in World War II made it the bloodiest conflict in history, as well as the biggest war. World War II, along with World War I, was one of the major watersheds in geopolitical history of the 20th century.

It resulted in the outgrowth of the power of the Soviet Union to Eastern European nations, enabled a communist party to eventually attain power in China, and marked the major shift of power in the world away from Western European states and towards the United States and the Soviet Union.

The war can be summarized through the given points below:

The Beginning (1939)

In late August 1939, the German-Soviet Nonaggression Pact was signed by Hitler and Soviet leader Joseph Stalin, inciting a frenzy of concern in London and Paris. Hitler had long plotted an invasion of Poland, a nation to which, if it was invaded by Germany, Great Britain and France would have provided military support.

The agreement with Stalin meant that once he invaded Poland, Hitler would not face a series of battles, and would have Soviet help in conquering and dividing the nation itself. Hitler invaded Poland from the west on September 1, 1939, while France and Britain declared war on Germany two days later, beginning World War II.

On 17 September, east Poland was invaded by Soviet troops. Poland fell rapidly under attack from both sides, and by early 1940 Germany and the Soviet Union had split power over the country, according to a secret agreement annexed to the Nonaggression Pact.

Stalin’s troops then pushed to occupy the Baltic States (Estonia, Latvia and Lithuania) and defeated a Finnish-Russian resistance. In the six months following Poland’s invasion, the lack of intervention on the part of Germany and the Allies in the West led to talk of a “real war” in the news media.

The Battle of Britain

German aircraft bombed Britain rigorously throughout the summer of 1940 to pave the way for an amphibious invasion, including night raids on London and other industrial areas that caused heavy civilian casualties and damage.

In the Battle of Britain, the Royal Air Force eventually defeated the German Air Force and Hitler delayed his plans to invade. With Britain’s defensive resources pushed over the edge, Prime Minister Winston Churchill started receiving crucial U.S. aid under the Lend-Lease Act, approved by Congress in early 1941.

In the late summer of 1940, Germany launched yet another attack on Britain, this time from the air alone. The Battle of Britain was Germany’s 1st military defeat, as the Luftwaffe, the German air force never managed to conquer the Royal Air Force of Britain.

The West (1940-41)

At the same time, Germany invaded Norway and occupied Denmark on April 9, 1940, and the war officially began. On May 10, German forces in what became known as the “blitzkrieg,” or lightning war, swept through Belgium and the Netherlands.

3 days later, Hitler’s troops crossed the Meuse River and attacked French forces at Sedan, situated on the northern end of the Maginot Line, an intricate series of fortifications built after World War I and considered an impenetrable barrier to the defence. In fact, the Germans with their planes and tanks broke through the line and moved on to the rear, rendering it useless.

The British Expeditionary Force (BEF) was evacuated from Dunkirk by the sea in late May, while a futile resistance was established in the French forces in the South. With France on the brink of collapse, Italy’s Benito Mussolini put his Steel Pact with Hitler into action and on June 10 Italy declared war on Britain and France.

On 14 June, German forces stormed Paris; two nights later, a new government established by Marshal Philippe Petain demanded an armistice. France was subsequently divided into two zones established at Vichy France, one under German military occupation and the other under Petain’s rule.

Then, Hitler focused his back to Britain which had the defensive benefit of being isolated by the English Channel from the Continent. By early 1941, Hungary, Romania and Bulgaria had joined the Axis, and German forces overran Yugoslavia and Greece that April. Hitler’s overthrow of the Balkans was a forerunner of his true aim: an invasion of the Soviet Union, whose vast territories would give the German imperial race the “Lebensraum” it required.

Operation Barbarossa (1941-42)

By early 1941, Hungary, Romania and Bulgaria had joined the Axis, and German forces overran Yugoslavia and Greece that April. Hitler’s overthrow of the Balkans was a forerunner of his true aim: an invasion of the Soviet Union, whose vast territories would give the German imperial race the “Lebensraum” it required.

The other half of Hitler’s plan was to exterminate the Jews from all over the occupied German Europe. Plans for the “Final Solution” were initiated at the time of the Soviet war, and more than 4 million Jews will be killed in the death camps in occupied Poland over the next three years.

Hitler ordered an invasion of the Soviet Union on 22 June 1941, code-named Operation Barbarossa. Although the Germans were largely outnumbered by Soviet jets and tanks, their air technology was largely obsolete, and the impact of the surprise invasion helped Germans reach Moscow by mid-July within 200 miles.

Hitler’s arguments with his commanders postponed the next German advance until October when a Soviet military operation and the onset of harsh winter weather stalled it. 

Pearl Harbor

The pacific war began on December 7, 1941, when Japanese warplanes launched a surprise assault on the US Pearl Harbor Marine Station, Hawaii. By this time Japan had been in war with China for several years already and had seized Manchuria’s Chinese territory. Japan launched a major expansion program in the Southeast Asia – Pacific area following the Pearl Harbor attack.

Battle of Midway

The U.S. Pacific Fleet won the Battle of Midway from June 3-6 of 1942 after a long series of Japanese successes The victory proved to be a turning point in the war in which Japan suffered a catastrophic defeat. 


The Allies also prevailed against Japanese forces in a series of battles on Guadalcanal, one of the southern Solomon Islands, from August 1942 to February 1943, helping turn the tide back into the Pacific. Armed naval forces launched an aggressive counterattack against Japan in mid-1943, including a series of amphibious attacks on main Japanese-held Pacific islands. This strategy of “island-hopping” proved to be successful, and Allied forces moved closer to their ultimate goal of invading Japanese home.

Battle of Stalingrad (1942-43)

On the Eastern Front of World War II, the bloody Battle of Stalingrad began with a Soviet counter-offensive launched in November 1942, which had seen some of the fiercest fightings. In addition to limited food and medical supplies, the arrival of winter marked the end for German troops. The remaining surrendered on January 31, 1943.

Battle of the Bulge (1944-45)

Celebrated as the “D-Day”, on the sixth of June, 1944, the Allies began a major European invasion, dropping 156,000 British, American, and Canadian, troops on Normandy beaches in France. In reaction, Hitler poured all of his army’s remaining power into Western Europe, guaranteeing eastward defeat for Germany.

Soviet troops soon marched into Czechoslovakia, Poland, Romania, and Hungary while in the Battle of the Bulge (December 1944-January 1945). Hitler mobilized his forces to push the Americans and British back from Germany. It was the last major German offensive of the war.

Intensive air bombings in February 1945 preceded the Allied invasion of Germany, and by the time Germany formally surrendered on 8 May, the Soviet forces had occupied a large part of the country. At that time, Hitler was already dead in his Berlin bunker. He died of suicide on 30th April.

Potsdam Conference

At the Potsdam Conference,1945, the U.S. President Harry S. Truman, Churchill and Stalin discussed both the ongoing war with Japan and the peace treaty with Germany. Post-war Germany will be divided into 4 zones of occupation to be administered by the Soviet Union, the United Kingdom, the United States and France. On the divisive question of the future of Eastern Europe, Churchill and Truman agreed with Stalin that they needed Soviet cooperation in the war against Japan.

The Manhattan Project

Heavy losses from campaigns of the Iwo Jima in February and Okinawa in April-June of 1945 and fears of even more expensive land invasion led Truman to approve the use of a modern and destructive arsenal. Developed during a top-secret operation called The Manhattan Project, the atom bomb was deployed at the beginning of August in the Japanese cities of Hiroshima and Nagasaki.

By the end of 1945, most of Japan’s victories had been destroyed, and the Allied powers were closing in on the home islands of Japan. When Japan advanced, the Allies launched heavy missile strikes against major Japanese cities, including Tokyo.

This process was continued through the summer of 1945 until the United States finally dropped two Atomic Bombs in the cities of Hiroshima and Nagasaki in August. Stunned by the unforeseen devastation, Japan surrendered within days.


The Second World War proved to be the world’s most dangerous conflict in history. It killed 60 to 80 million people, including 6 million Jews who died at the hands of the Nazis during the Holocaust. Citizens were believed to have killed between 50 and 55 million people during the war, while the army accounted for between 21 and 25 million of those lost during the war. Millions more were wounded, and their homes and properties were lost even more.

(Last Updated On: November 12, 2020)