World War II - Key Events, Causes, and Impact

Changing the course of history, World War II was one of the 20th century’s defining events, involving over 30 countries and affecting more than 100 million people worldwide.

How did WWII begin?

World War II (WWII) began in Europe in September 1939 when Germany, led by dictator Adolf Hitler, invaded Poland. Britain and France, honouring their alliance with Poland, declared war on Germany two days later.

Who was involved?

From 1939 to 1945, WWII involved most of the world. The main conflict was between the Axis powers – Germany, Italy, and Japan – and the Allies – Britain, France, the Soviet Union, the United States, and later China.

How long did WWII last?

The war lasted six years, from 1939 until 1945.

Key Events

September 1939 -  War breaks out

Germany invaded Poland, and as a result, Britain and France declare war.

May-July 1940 -  Fall of France and the Battle of Britain

The Battle of France began in May 1940 as Germany invaded France and Belgium, amongst others. As a result, British forces based in Dunkirk were forced to evacuate and shortly after, France surrendered.

Only a couple of months later in July 1940, Germany attempted to gain air control over the British Isles. The Royal Air Force defeated the German Air Force (known as the Luftwaffe), which delayed the invasion.

September 1940 -  The beginning of the Blitz

Later that year marked the start of the Blitz, and Germany began to aerial bomb British cities. The raids began on 7 September when a large-scale attack took place in London. Across the months that the bombings took place, over 40,000 civilian lives were lost.

June 1941 -  Operation Barbarossa

In June 1941, despite Germany and the Soviet Union having a pact not to inflict aggression on one another, Hitler invaded the Soviet Union. This marked the beginning of the Eastern Front of the Second World War, which was a major combat primarily between the two nations, lasting from 1941 to 1945 and involving mass casualties.

December 1941 -  Pearl Harbour

In July 1941, the war expanded. Japan sent troops to South-East Asia, threatening British interests in the area. As a result, in August 1941 the US imposed an oil embargo on Japan, cutting off most of their imported oil supply.

This sparked a huge conflict between the two countries. In retaliation to this, on 7 December 1941, Japan launched an attack on Pearl Harbour – the US Navy’s Pacific Fleet. The US declared war on Japan the next day.

Following this, the Japanese also invaded British territories in Hong Kong, Malaya, Singapore and Burma, as well as other European colonies within Eastern Asia. They wanted to create a perimeter around Japan, with the aim of defending captured territories until the war settled.

February 1942 -  Fall of Singapore

In February 1942, 80,000 commonwealth troops were taken prisoner by Japan in Singapore. This was following a crisis in what was once a city; Singapore was surrounded and cut off meaning it had little supplies, such as water. This led to its surrender.

June 1942 - Battle of Midway

The Battle of Midway took place in the June of this year. The US Navy severely weakened the Japanese naval power in the Pacific, leading to a victory at Midway.

February 1943 -  Battle of Stalingrad

February 1943 marked a major turning point in the Second World War. The Soviet Union successfully defended the city of Stalingrad against the Nazi German army, and on 2 February, the German Sixth Army surrendered. The Soviet Red Army began to push Germany back towards Berlin.

July 1943 - Allied invasion of Sicily

Following their success in North Africa, Allied forces invaded Sicily. 150,000 allied troops landed on Sicily, and slowly advanced through Italy before being held up by German resistance.

September 1943 -  Italy surrendered to the Allies

On 3 September, 1943, Italy made a major shift in the war. After suffering several defeats, the country’s new leader, Marshal Pietro Badoglio, negotiated peace with the Allies. As a result, Italian forces immediately stopped fighting against them and effectively switched sides.

June 1944 -  D-Day

D-Day is one of the most significant events that took place in WWII. At this stage of the war, Germany was occupying France and much of the rest of Europe after Germany’s conquest.

On 6 June 1944,  allied countries – Britain, America and Canada – planned to land on the beaches in Normandy, and free France from being ruled by Germany.

To deceive Germany,  hundreds of fake planes were built and placed near Dover to convince German pilots  flying over Britain, that an invasion was going to take place at Calais. This helped  allied troops arrive at Normandy with less resistance from  German troops and force them back.

December 1944 -  Battle of the Bulge

By late 1944, Germany was in retreat on both the Eastern and Western Fronts. Allied commanders believed Germany lacked the resources for another offensive, but Hitler launched one final gambit.

His plan was to drive through the Ardennes, cross the Meuse River, and capture Antwerp. This would split British and American forces, potentially sparking disagreements that might lead the Allies to negotiate, allowing Germany to focus on the Soviets in the East.

The attack initially created a ‘bulge’ in Allied lines, but strong Allied resistance soon stopped the advance. By early January 1945, the Allies counterattacked from both North and South, forcing a German retreat. By March, German forces had been pushed back across the Rhine, making their last major offensive in the West unsuccessful.

April 1945 - Battle of Okinawa

Fought from 1 April to 21 June 1945, the Battle of Okinawa was a major clash between US and Japanese forces. It was the last island battle before the planned invasion of mainland Japan and one of the bloodiest of the Pacific War, costing over 12,000 American and 100,000 Japanese lives.

May 1945 -  Victory in Europe            

Victory in Europe Day, also known as VE Day, marked the end of the war in Europe.

On 30 April 1945, shortly after Berlin was surrounded, Adolf Hitler took his own life, leaving Germany’s rule to his named successor, Grand Admiral Karl Dönitz. Dönitz wanted to save as many people as possible from falling into the hands of the Soviets, and as a result, negotiated with the Allies to end the war.

VE Day was officially 8 May 1945, but many people began their celebrations early when the news broke out on 7 May.

August 1945 -  VJ Day – Ending of WWII

On 6 August 1945, the United States dropped the first atomic bomb on Hiroshima, followed by a second on Nagasaki three days later. The bombings caused massive destruction and at least 120,000 deaths.

On 10 August, Japan began negotiating surrender, but only under certain conditions. The Allies demanded unconditional surrender, which Japan accepted on 14 August. Victory over Japan Day (VJ Day) was declared on 15 August. The formal surrender was signed aboard the USS Missouri in Tokyo Bay on 2 September, officially ending World War II.

To find out more about VJ Day, visit our blog post.

How many casualties were in WWII?

WWII is considered the deadliest conflict in history, with an estimated 40–50 million deaths. The Soviet Union suffered the highest losses – over 20 million. In Britain, more than 380,000 soldiers and 70,000 civilians died, over half during the Blitz.

How did WWII end?

The war in Europe ended on 8 May 1945 with Germany’s surrender. The conflict continued in Asia until 2 September 1945, when Japan officially surrendered, marking the end of WWII.

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