The main phases of the war, 1939 to 1945

1The war at a glance

Counted from the German invasion of Poland on 1 September 1939 to Japan's formal surrender on 2 September 1945, the Second World War lasted six years and a day. It was fought in two main theatres: Europe and North Africa, where Germany and Italy were the main Axis powers, and Asia and the Pacific, where Japan fought China, the United States and the British Empire. Study the timeline before you read on.

Figure 1. The war at a glance. The band is drawn to scale, one month to about 7 pixels.

Reading the timeline. In phase 1 every arrow of the war points the Axis way. Phase 2 is short but decisive: in six months Germany attacked the Soviet Union and Japan attacked the United States, so the two strongest powers outside the Axis entered the war. In phase 3 the Axis advance was stopped on land, at sea and in the desert, and in phase 4 the Allies closed in on Germany and Japan from several sides. Historians divide the war in slightly different ways, but most agree on these turning points.

2Phase 1. Axis victories, September 1939 to June 1941

• Poland was defeated in about five weeks by German Blitzkrieg from the west and the Soviet army from the east.
• In the west a quiet winter, the "Phoney War", followed. In April 1940 Germany took Denmark and Norway.
• On 10 May 1940 Germany attacked the Netherlands, Belgium, Luxembourg and France. German tanks broke through the Ardennes forest and trapped the Allied armies against the sea. Between 26 May and 4 June 1940 more than 338,000 Allied soldiers were rescued from the beaches of Dunkirk. Italy entered the war on 10 June, and France signed an armistice on 22 June 1940. Germany occupied the north of France; in the south, Marshal Pétain led a government at Vichy that worked with the Germans.
• Britain fought on alone in Europe, under Winston Churchill. In the Battle of Britain, from July to October 1940, the Royal Air Force defeated the German air force's attempt to win control of the skies, and Hitler put off his invasion of Britain.
• In September 1940 Germany, Italy and Japan signed the Tripartite Pact. In April 1941 German forces conquered Yugoslavia and Greece. Italian forces had attacked British Somaliland and Egypt in 1940: Lesson 3 follows the war in Africa.

3Phase 2. The war goes global, June 1941 to mid-1942

On 22 June 1941 Germany broke the Nazi–Soviet Pact and invaded the Soviet Union with more than 3.8 million Axis soldiers (Operation Barbarossa), on a front about 2,900 kilometres long. By December German troops were close to Moscow, but the Soviet army counter-attacked in the freezing winter, and the quick victory Hitler expected never came.

On 7 December 1941 Japanese aircraft carriers attacked the American naval base at Pearl Harbor, in Hawaii. Japan wanted to destroy the American fleet so that it could seize the oil, rubber and tin of South-East Asia, after the United States had stopped selling it oil. All eight American battleships in the harbour were damaged and four were sunk. The United States declared war on Japan the next day, and on 11 December Germany and Italy declared war on the United States. In the next months Japan conquered Hong Kong, Malaya, Singapore (15 February 1942), the Philippines, the Dutch East Indies and Burma.

4Phase 3. The turning points, mid-1942 to 1943

1. Midway, 4 to 7 June 1942. American aircraft sank four Japanese aircraft carriers near Midway island in the Pacific. Japan never recovered the lost carriers and trained pilots, and from now on it was on the defensive.
2. El Alamein, October and November 1942. In Egypt the British Eighth Army, with soldiers from across the Empire, defeated the German and Italian army of Erwin Rommel. Days later, on 8 November, American and British troops landed in Morocco and Algeria. By May 1943 the Axis armies in North Africa had surrendered.
3. Stalingrad, August 1942 to February 1943. The German Sixth Army was surrounded in the ruined city on the Volga river and surrendered on 2 February 1943. In July 1943 the Soviets also won the great tank battle of Kursk, and from then on the Red Army advanced west.
4. Italy. The Allies landed in Sicily in July 1943, Mussolini was overthrown, and Italy signed an armistice in September 1943 (Unit 4).
5. The Atlantic. By mid-1943 radar, code-breaking and air patrols had defeated the German submarines (U-boats) that had been sinking the ships carrying food and weapons to Britain.

5Phase 4. Allied victory, 1944 to 1945

On 6 June 1944, "D-Day", American, British, Canadian and other Allied troops landed on the beaches of Normandy in northern France: the largest amphibious landing in history. Paris was liberated on 25 August 1944. In the east, a vast Soviet offensive in the summer of 1944 destroyed a whole German army group. Germany's last attack in the west, in the Ardennes in December 1944, failed. With Soviet troops in Berlin, Hitler killed himself on 30 April 1945, and Germany surrendered on 8 May 1945, "Victory in Europe Day".

In the Pacific, American forces advanced from island to island towards Japan, while British, Indian and African troops drove the Japanese out of Burma. Japan fought on even after Germany fell. On 6 August 1945 the United States dropped an atomic bomb on Hiroshima, and on 9 August a second on Nagasaki. The two bombs killed an estimated 150,000 to 246,000 people, most of them civilians. On 8 August the Soviet Union declared war on Japan and invaded Manchuria. Emperor Hirohito announced Japan's surrender on 15 August, and the formal surrender was signed on 2 September 1945.

We hereby proclaim the unconditional surrender to the Allied Powers of the Japanese Imperial General Headquarters and of all Japanese armed forces and all armed forces under the Japanese control wherever situated.

Source D. Instrument of Surrender, signed in Tokyo Bay, 2 September 1945. Text: the Avalon Project, Yale Law School.

6Why the Allies won

• Resources. Once the United States and the Soviet Union had joined, the Allies had far more people, oil and factories. American industry produced more weapons than all the Axis powers together.
• Axis mistakes. Hitler attacked the Soviet Union before Britain was beaten, and declared war on the United States; Japan provoked the United States into the war.
• Turning-point victories at Midway, El Alamein and Stalingrad ended the Axis advance in 1942 and 1943.
• Command of the sea and the air, won in the Atlantic and over Germany and Japan, allowed the Allies to land armies where they chose.
• Science and intelligence: radar, code-breaking and, at the end, the atomic bomb.

7Discuss

The atomic bombings ended the war quickly but killed tens of thousands of civilians in an instant. Historians still debate whether they were necessary. What questions would you need to answer before you could judge? Think about the laws of war you met in Unit 4, and about who decides what is "necessary".