Many called the First World War (1914-1918) "the war to end war."1 And yet, only two decades later, most of the world was engaged in the biggest and deadliest armed conflict in recorded history, the Second World War (1939-1945). World War II was a complex event fought on different continents between the Allies and Axis Powers. In 1945, the world changed dramatically, not only because of the war's devastation but also because of the rearrangement of the global order.
Fig. 1 - Nazi German advance on Moscow in October 1941
World War II Summary
The Second World War (1939-1945) was the bloodiest conflict in the history of humankind. The war was fought between the Allies and Axis Powers in Europe, Africa, and Asia. Its death toll is difficult to determine with some estimates being upward of 70 million.
The greatest loss of life occurred in the Soviet Union (an estimated 27 million) and China (an estimated 20 million).
World War II: Causes
Historians identify several long-term and short-term causes of World War II.
Long-Term Causes
- The terms of the Treaty of Versailles (1919)
- The Great Depression (1929)
- Militarism in Germany and Japan
- German Nazism
- Japanese imperialism
- The League of Nations' inability to prevent war
Short-Term Causes
- The Mukden Incident (1931) and Japan's invasion of China in 1937 (Second Sino-Japanese War)
- The Italian invasion of Ethiopia (1935)
- German annexation of Austria (1938) and Czechoslovakia (1938) and the invasion of Poland (1939)
World War II: Countries
The Second World War was fought between the Allies and the Axis Powers.
| Name | Countries |
| Allied Powers | - The Allies were led by the Big Three: the Soviet Union, Britain, and the U.S.
- Other Allies included China, Canada, Australia, Poland, and many others.
|
| Axis Powers | - The Axis Powers were led by Nazi Germany, Japan, and Italy with support from Romania, Bulgaria, Croatia, Finland, and others.
- The leadership was: Adolf Hitler (Germany), Benito Mussolini (Italy), and Emperor Hirohito (Japan).
|
World War II: Allies
The Big Three (Grand Alliance) led several Allied countries to victory in Europe on May 8, 1945, and in Japan on September 2, 1945. The Allied leaders were:
- Joseph Stalin (Soviet Union)
- Winston Churchill (Britain)
- Franklin D. Roosevelt (United States) followed by Harry Truman after April 1945
The Allied leadership met at wartime conferences to discuss joint strategy as well as the global order after the war:
- Casablanca, January 14-24, 1943*
- Cairo, November 22-26, 1943*
- Tehran, November 28-December 1, 1943
- Yalta, February 4-11, 1945
- Potsdam, July 17-August 2, 1945
*excluding Stalin.
Axis Initiative and Allied Reaction
The Second World War was a very complex event fought in multiple war theaters, including:
- Europe
- Asia-Pacific
- North Africa
Initially, the Axis Powers were successful.
For example, Germany invaded Poland on September 1, 1939, the Soviet Union on June 22, 1941, and Japan bombed Pearl Harbor, U.S. on December 7, 1941.
The Allies generally responded to these actions. As time went on, the momentum shifted to the Allied side.
For instance, the Soviet Union's Operation Bagration pushed Germany westward. Bagration overlapped with the Anglo-American Operation Overlord in the summer of 1944 forcing Nazi Germany to fight both on the eastern and western fronts.
Fig. 2 - German Luftwaffe bomber over East London, September 7, 1940
World War II: Axis Powers
In addition to Germany occupying much of Europe and Africa, it is important to look at Japan and Italy briefly.
Japan
Japan annexed Korea in 1910 and Chinese Manchuria in 1931. Japan called its empire the Greater East Asia Co-Prosperity Sphere. During the war, Japan invaded:
- Vietnam
- Burma (Myanmar)
- Laos
- Thailand
- Cambodia
- Philippines
Japan primarily fought the United States in the Asia-Pacific theater.
Italy
Between 1922 and 1943, fascist Benito Mussolini ruled Italy. Mussolini sought to expand its African colonies by acquiring Tunisia and Algeria, but they were under the German collaborationist Vichy regime. Italy invaded places like Egypt and fought the British troops in Africa. The fascist government collapsed in 1943, and the Allied liberation of Italy began.
World War II: Timelines
Many major events took place during the war, including:
| Date | Event |
| September 1, 1939 | - Germany invaded Poland
- WWII began
- In 1940, Germany steamrolled over western Europe (France, Belgium, Netherlands, et al).
|
| September 3, 1939 | - France and Britain declared war on Germany.
|
| June 10-25, 1940 | |
| June 22, 1940 | - France surrendered to Nazi Germany and formed the Vichy regime.
- Free France, under Charles de Gaulle, was an Allied power in exile.
|
| July 10-October 31, 1940 | - The Battle of Britain was the first major airborne campaign.
|
September 7, 1940–May 11, 1941 | - The Blitz: Nazi German aerial bombing campaigned against Britain.
|
| December 7, 1941 | - Japan strikes Pearl Harbor, Hawaii.
- The U.S. declared war on Japan the next day.
|
| December 11, 1941 | - Germany declared war on the U.S.
|
| - Britain and US invaded North Africa (Operation Torch): this is the first American engagement outside the Asia-Pacific theater.
|
| June 22, 1941 | - Germany invaded the Soviet Union (Operation Barbarossa). In the fall, the Germans were within 50 km of Moscow.
|
| August 1941–May 1945 | - 78 Arctic Convoys (UK, US, Canada, Norway) delivered supplies to the Soviet Union under the American Lend-Lease agreement.
|
| June 4-7, 1942 | - The Battle of Midway was the Asia-Pacific war theater's first important turning point.
|
| August 23, 1942-2 February 2, 1943 | - The Battle of Stalingrad was one of the bloodiest battles in history with approximately a million dead on each side.
- A turning point on the eastern front in Allied favor.
|
| June 6, 1944-August 30, 1944 | - Operation Overlord (Normandy Landings) launched the second front in continental Europe led by Anglo-Americans.
- Up until this point, the Soviet Red Army singlehandedly fought on the eastern front and, overall, was responsible for up to 80% of Nazi German losses.
|
| June 22-August 19 1944 | - The Soviet Union launched Operation Bagration two weeks after Overlord to drain Germany on two fronts simultaneously.
|
| October 17–December 26, 1944 | - The Battle of Leyte in the Pacific was the largest naval battle in history.
|
| January 27, 1945 | - The Soviet Red Army liberated Auschwitz, Monowitz, and Birkenau Nazi concentration camps.
|
| April 25, 1945 | - Elbe Day: Soviet and American troops linked up.
|
| April 16, 1945-May 2, 1945 | - The Soviet Red Army took Berlin in the Battle of Berlin.
|
| May 8, 1945 | - Victory over Germany in Europe.
|
| August 6, 9 1945 | - The US dropped atomic bombs on Hiroshima and Nagasaki, Japan.
|
| August 8, 1945 | - The Soviet Union entered the war against Japan.
|
| September 2, 1945 | |
Fig. 3 - Europe at the height of Nazi German occupation, 1941-1942, Creative Commons Attribution-Share Alike 4.0 International license
Rise of the Third Reich: WWII and the Nazi Party
Adolf Hitler (1889-1945) came into power as Chancellor of Germany in 1933 after involvement with the Nazi (National-Socialist) Party for several years. Hitler's beliefs included:
- Grievances over the unfair terms of the Treaty of Versailles after WWI in which Germany was to pay reparations and lost historical territories. These terms sent Germany into economic turmoil in the 1920s.
- Racial superiority of the "Aryan race" over others, especially the Jews, Slavs, and the Roma.
- Lebensraum ("living space"): an expansionist ideology seeking to conquer others' land, especially the Soviet Union, for ethnic Germans.
- Militarism.
Fig. 4 - Adolf Hitler and Benito Mussolini
In the lead-up to WWII, Hitler pursued his goal of the Third Reich "super state" by:
- establishing and enlarging the Wehrmacht (armed forces)
- creating an air force
- building up a fleet of U-boats
These actions contradicted the terms of the Treaty of Versailles, including:
- Remilitarization of Rhineland
- Annexation of Austria
When Hitler went to reclaim the historical German Sudetenland in Czechoslovakia, Britain, France, and Italy decided to acknowledge Germany's annexation of that territory through the 1938 Munich Agreement, on the condition that Hitler would not attempt any further expansion. Some historians called it appeasement. On September 1, 1939, Hitler's army invaded Poland. Britain and France declared war on Germany, and the Second World War began.
Nazi Occupation in WWII
By the middle of 1940, Germany was occupying much of Western Europe. They had achieved this feat by engaging in a military tactic that came to be called Blitzkrieg ("lightning war") which combined the elements of speed, surprise, and military power. Some historians consider Blitzkrieg to be highly effective and responsible for Germany's swift occupation of Europe.
German tactics involved:
- Surprise bombings on locations like military or communication headquarters and bridges
- Large brigades of tanks and heavy artillery would sweep through enemy territory
- Paratroopers were placed in strategic positions in enemy territory to prevent retreats or interfere with supply lines
Despite these initial successes, the Allies were able to challenge Germany all the way to victory.
The Holocaust in WWII
Shortly after Hitler came into power in 1933, the Dachau concentration camp was opened. Labeled as a camp for political prisoners, it soon became one of the death camps where thousands of Jewish people were killed during the war. The Nazis targeted the Jews and other minorities based on their hierarchic racialist ideas.
The Jews were one of the key targeted groups during WWII with a staggering six million killed. Out of the other minority groups, the Romani people were also heavily targeted. Hundreds of thousands of Roma were killed at camps alongside Jews, Slavs, disabled people, LGBTQ+, and others perceived to be inferior by the Nazis.
Fig. 5 - the Romani people
The Nazis used:
- extermination camps
- labor camps
- ghettos
for those they perceived inferior.
Some locations include:
- Dachau
- Auschwitz
- Birkenau
- Treblinka
- Majdanek
In camps, people died from overwork, starvation, and disease or were killed in gas chambers.
Did you know?
The largest ghetto during the Nazi occupation was in Warsaw, Poland.
Fig. 6 - Prisoners in the Ebensee concentration camp
Medical experimentation was also a frequent occurrence in concentration camps. Thousands fell victim to the cruel and frequently deadly experiments by German doctors done on behalf of the German army, pharmaceutical companies, and sometimes for the doctors' own interests.
For example, Doctor Josef Mengele performed deadly medical experiments on people in the Birkenau camp. After the war, Mengele managed to evade the Nuremberg war crime trials and died in South America in 1979.
Fig. 7 - Montgomery (UK), Zhukov (Soviet Union), and Rokossovsky (Soviet Union) at the Brandenburg Gate, Berlin, 1945
The End of War War II
After the launch of the second front in continental Europe through Normandy Landings, the Allies wore down the Nazi war machine. The Americans and Soviets linked up in Germany in April 1945. A victory was declared on May 8, 1945 (V/E Day) by the western Allies, and May 9 (Victory Day) for the Soviet Union.
In the Asia-Pacific theater, Japan was suffering defeat after defeat but did not officially surrender. Some scholars believe the latter to be linked to Japanese culture. President Harry Truman ordered the use of atomic bombs on Hiroshima and Nagasaki on August 6 and 9, 1945, respectively. Their use led to a large civilian death toll of up to 200,000 and injuries, cancer, and radiation birth defects.
Some historians believe that Truman wanted to show off these new weapons to its wartime ally and a new ideological rival, the Soviet Union. On September 2, 1945, Japan signed official surrender documents, and WWII came to an end.
Fig. 8 - Mamoru Shigemitsu signing the Instrument of Surrender on September 2, 1945
WWII - Key Takeaways
- World War II (1939-1945) was the biggest armed conflict in history that took place on multiple continents with an estimated death toll of upward of 70 million. The main Allies were the Soviet Union, Britain, and the United States. The Axis Powers were Germany, Italy, and Japan.
- The war had many long-term and short-term causes including the Treaty of Versailles, German Nazism, and Japanese imperialism.
- Germany occupied much of Europe and Japan—Asia. Turning points in favor of the Allies came in 1942/1943.
- Allied cooperation at wartime conferences defined the overall strategy.
- The Second World War led to significant changes in the global order.
References
- Wells, H.G., The War That Will End War, London: Frank and Cecil Palmer, 1914, title page.
- Fig. 2 - Europe at the height of Nazi German occupation, 1941-1942 (https://commons.wikimedia.org/wiki/File:World_War_II_in_Europe,_1942.svg) by Goran tek-en (https://commons.wikimedia.org/wiki/User:Goran_tek-en), licensed under the Creative Commons Attribution-Share Alike 4.0 International license (https://creativecommons.org/licenses/by-sa/4.0/deed.en).
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