World War II
Clockwise from top left: Chinese forces in the Battle of Wanjialing, Australian 25-pounder guns during the First Battle of El Alamein, German Stuka dive bombers on the Eastern Front winter 1943–1944, US naval force in the Lingayen Gulf, Wilhelm Keitel signing the German Surrender, Soviet troops in the Battle of Stalingrad
Date 1 September 1939 (1939-09-01) – 2 September 1945 (1945-09-02) (&100000000000000060000006 years, &100000000000000010000001 day) Location Europe, Pacific, Atlantic, South-East Asia, China, Middle East, Mediterranean and Africa, briefly North America Result Allied victory Dissolution of the Third Reich Creation of the United Nations Emergence of the United States and the Soviet Union as superpowers Beginning of the Cold War. (more...)
Belligerents
Allies 22x20px Soviet Union (1941–45)[nb 1]  United States (1941–45)  British Empire China (at war 1937–45)  France[nb 2]  Poland  Canada  Australia  New Zealand  South Africa  Yugoslavia (1941–45)  Greece (1940–45)  Norway (1940–45)  Netherlands (1940–45)  Belgium (1940–45)  Czechoslovakia  Brazil (1942–45) ...and others Client and puppet states Philippines (1941–45) Mongolia (1941–45) ...and others	Axis  Germany  Japan (at war 1937–45)  Italy (1940–43)  Hungary (1940–45)  Romania (1941–44)  Bulgaria (1941–44) Co-belligerents  Finland (1941–44)  Thailand (1942–45) 22x20px Iraq (1941) Client and puppet states  Manchukuo  Italian Social Republic (1943–45)  Independent State of Croatia (1941–45)  Slovakia ...and others
Commanders and leaders
Allied leaders 22x20px Joseph Stalin Franklin D. Roosevelt Winston Churchill Chiang Kai-shek Charles de Gaulle ...and others	Axis leaders Adolf Hitler Hirohito Benito Mussolini ...and others
Casualties and losses
Military dead: Over 16,000,000 Civilian dead: Over 45,000,000 Total dead: Over 61,000,000 (1937–45) ...further details	Military dead: Over 8,000,000 Civilian dead: Over 4,000,000 Total dead: Over 12,000,000 (1937–45) ...further details

World War II, or the Second World War (often abbreviated as WWII or WW2), was a global war that was under way by 1939 and ended in 1945. It involved a vast majority of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis. It was the most widespread war in history, with more than 100 million people serving in military units. In a state of "total war", the major participants placed their entire economic, industrial, and scientific capabilities at the service of the war effort, erasing the distinction between civilian and military resources. Marked by significant events involving the mass death of civilians, including the Holocaust and the only use of nuclear weapons in warfare, it resulted in 50 million to over 70 million fatalities. These deaths make the war the deadliest conflict in human history.^[1]

Although Japan was already at war with China in 1937,^[2] the world war is generally said to have begun on 1 September 1939, with the invasion of Poland by Germany, and subsequent declarations of war on Germany by France and most of the countries of the British Empire and Commonwealth. Germany set out to establish a large empire in Europe. From late 1939 to early 1941, in a series of campaigns and treaties, Germany conquered or subdued much of continental Europe; amid Nazi-Soviet agreements, the nominally neutral Soviet Union fully or partially invaded, occupied and annexed territories of its six European neighbours, including Poland. Britain and the Commonwealth remained the only major force continuing the fight against the Axis, with battles taking place in North Africa as well as the long-running Battle of the Atlantic. In June 1941, the European Axis launched an invasion of the Soviet Union, giving a start to the largest land theatre of war in history, which tied down the major part of the Axis' military forces. In December 1941, Japan, which aimed to dominate Asia and join the Axis, attacked the United States and European possessions in the Pacific Ocean, quickly conquering much of the West Pacific.

The Axis advance was stopped in 1942, after Japan lost a series of naval battles and European Axis troops were defeated in North Africa and, decisively, at Stalingrad. In 1943, with a series of German defeats in Eastern Europe, the Allied invasion of Fascist Italy, and American victories in the Pacific, the Axis lost the initiative and undertook strategic retreat on all fronts. In 1944, the Western Allies invaded France, while the Soviet Union regained all of its territorial losses and invaded Germany and its allies. The war in Europe ended with the capture of Berlin by Soviet and Polish troops and the subsequent German unconditional surrender on 8 May 1945. During 1944 and 1945 the United States defeated the Japanese Navy and captured key West Pacific islands, dropping atomic bombs on the country as the invasion of the Japanese Archipelago ("Home Islands") became imminent. The war in Asia ended on 15 August 1945 when Japan agreed to surrender.

The total victory of the Allies over the Axis in 1945 ended the conflict. World War II altered the political alignment and social structure of the world. The United Nations (UN) was established to foster international cooperation and prevent future conflicts. The great powers that were the victors of the war—the United States, Soviet Union, China, Britain, and France—became the permanent members of the UN's Security Council.^[3] The Soviet Union and the United States emerged as rival superpowers, setting the stage for the Cold War, which lasted for the next 46 years. Meanwhile, the influence of European great powers started to decline, while the decolonisation of Asia and Africa began. Most countries whose industries had been damaged moved towards economic recovery. Political integration, especially in Europe, emerged as an effort to stabilise postwar relations.

Chronology[link]

The start of the war is generally held to be 1 September 1939, beginning with the German invasion of Poland; Britain and France declared war on Germany two days later. Other dates for the beginning of war include the start of the Second Sino-Japanese War on 7 July 1937.^[4][5]

Others follow British historian A. J. P. Taylor, who held that the Sino-Japanese War and war in Europe and its colonies occurred simultaneously and the two wars merged in 1941. This article uses the conventional dating. Other starting dates sometimes used for World War II include the Italian invasion of Abyssinia on 3 October 1935.^[6]

The exact date of the war's end is also not universally agreed upon. It has been suggested that the war ended at the armistice of 14 August 1945 (V-J Day), rather than the formal surrender of Japan (2 September 1945); in some European histories, it ended on V-E Day (8 May 1945). However, the Treaty of Peace with Japan was not signed until 1951,^[7] and that with Germany not until 1990.^[8]

Background[link]

World War I radically altered the political map, with the defeat of the Central Powers, including Austria-Hungary, Germany and the Ottoman Empire; and the 1917 Bolshevik seizure of power in Russia. Meanwhile, existing victorious Allies such as France, Belgium, Italy, Greece and Romania gained territories, while new states were created out of the collapse of Austria-Hungary and the Russian and Ottoman Empires.

In the aftermath of the war, irredentist and revanchist nationalism became important in a number of European states. Irredentism and revanchism were strong in Germany because of the significant territorial, colonial, and financial losses incurred by the Treaty of Versailles. Under the treaty, Germany lost around 13 percent of its home territory and all of its overseas colonies, while German annexation of other states was prohibited, reparations were imposed, and limits were placed on the size and capability of the country's armed forces.^[9] Meanwhile, the Russian Civil War had led to the creation of the Soviet Union.^[10]

The German Empire was dissolved in the German Revolution of 1918–1919, and a democratic government, later known as the Weimar Republic, was created. The interwar period saw strife between supporters of the new republic and hardline opponents on both the right and left. Although Italy as an Entente ally made some territorial gains, Italian nationalists were angered that the promises made by Britain and France to secure Italian entrance into the war were not fulfilled with the peace settlement. From 1922 to 1925, the Fascist movement led by Benito Mussolini seized power in Italy with a nationalist, totalitarian, and class collaborationist agenda that abolished representative democracy, repressed socialist, left wing and liberal forces, and pursued an aggressive foreign policy aimed at forcefully forging Italy as a world power—a "New Roman Empire".^[11] In Germany, the Nazi Party led by Adolf Hitler sought to establish a fascist government in Germany. With the onset of the Great Depression, domestic support for the Nazis rose and, in 1933, Hitler was appointed Chancellor of Germany. In the aftermath of the Reichstag fire, Hitler created a totalitarian single-party state led by the Nazis.^[12]

The Kuomintang (KMT) party in China launched a unification campaign against regional warlords and nominally unified China in the mid-1920s, but was soon embroiled in a civil war against its former Chinese communist allies.^[13] In 1931, an increasingly militaristic Japanese Empire, which had long sought influence in China^[14] as the first step of what its government saw as the country's right to rule Asia, used the Mukden Incident as a pretext to launch an invasion of Manchuria and establish the puppet state of Manchukuo.^[15] Too weak to resist Japan, China appealed to the League of Nations for help. Japan withdrew from the League of Nations after being condemned for its incursion into Manchuria. The two nations then fought several battles, in Shanghai, Rehe and Hebei, until the Tanggu Truce was signed in 1933. Thereafter, Chinese volunteer forces continued the resistance to Japanese aggression in Manchuria, and Chahar and Suiyuan.^[16]

Adolf Hitler, after an unsuccessful attempt to overthrow the German government in 1923, became the Chancellor of Germany in 1933. He abolished democracy, espousing a radical, racially motivated revision of the world order, and soon began a massive rearmament campaign.^[17] Meanwhile, France, to secure its alliance, allowed Italy a free hand in Ethiopia, which Italy desired as a colonial possession. The situation was aggravated in early 1935 when the Territory of the Saar Basin was legally reunited with Germany and Hitler repudiated the Treaty of Versailles, accelerated his rearmament programme and introduced conscription.^[18]

Hoping to contain Germany, the United Kingdom, France and Italy formed the Stresa Front. The Soviet Union, concerned due to Germany's goals of capturing vast areas of eastern Europe, wrote a treaty of mutual assistance with France. Before taking effect though, the Franco-Soviet pact was required to go through the bureaucracy of the League of Nations, which rendered it essentially toothless.^[19][20] However, in June 1935, the United Kingdom made an independent naval agreement with Germany, easing prior restrictions. The United States, concerned with events in Europe and Asia, passed the Neutrality Act in August.^[21] In October, Italy invaded Ethiopia, and Germany was the only major European nation to support the invasion. Italy subsequently dropped its objections to Germany's goal of absorbing Austria.^[22]

Hitler defied the Versailles and Locarno treaties by remilitarizing the Rhineland in March 1936. He received little response from other European powers.^[23] When the Spanish Civil War broke out in July, Hitler and Mussolini supported the fascist and authoritarian Nationalist forces in their civil war against the Soviet-supported Spanish Republic. Both sides used the conflict to test new weapons and methods of warfare,^[24] with the Nationalists winning the war in early 1939. In October 1936, Germany and Italy formed the Rome-Berlin Axis. A month later, Germany and Japan signed the Anti-Comintern Pact, which Italy would join in the following year. In China, after the Xi'an Incident the Kuomintang and communist forces agreed on a ceasefire in order to present a united front to oppose Japan.^[25]

Pre-war events[link]

Invasion of Ethiopia[link]

The Second Italo–Abyssinian War was a brief colonial war that began in October 1935 and ended in May 1936. The war was fought between the armed forces of the Kingdom of Italy (Regno d'Italia) and the armed forces of the Ethiopian Empire (also known as Abyssinia). The war resulted in the military occupation of Ethiopia and its annexation into the newly created colony of Italian East Africa (Africa Orientale Italiana, or AOI); in addition, it exposed the weakness of the League of Nations as a force to preserve peace. Both Italy and Ethiopia were member nations, but the League did nothing when the former clearly violated the League's own Article X.^[26]

Spanish Civil War[link]

The ruins of Guernica after the bombing.

Germany and Italy lent support to the Nationalist insurrection led by general Francisco Franco in Spain. The Soviet Union supported the existing government, the Spanish Republic, which showed leftist tendencies. Both Germany and the USSR used this proxy war as an opportunity to test improved weapons and tactics. The deliberate Bombing of Guernica by the German Condor Legion in April 1937 contributed to widespread concerns that the next major war would include extensive terror bombing attacks on civilians.^[27][28]

Japanese invasion of China[link]

A Chinese machine gun nest in the Battle of Shanghai, 1937.

In July 1937, Japan captured the former Chinese imperial capital of Beijing after instigating the Marco Polo Bridge Incident, which culminated in the Japanese campaign to invade all of China.^[29] The Soviets quickly signed a non-aggression pact with China to lend materiel support, effectively ending China's prior cooperation with Germany. Generalissimo Chiang Kai-shek deployed his best army to defend Shanghai, but after three months of fighting, Shanghai fell. The Japanese continued to push the Chinese forces back, capturing the capital Nanking in December 1937 and committed the Nanking Massacre.

In June 1938, Chinese forces stalled the Japanese advance by flooding the Yellow River; this manoeuvre bought time for the Chinese to prepare their defenses at Wuhan, but the city was taken by October.^[30] Japanese military victories did not bring about the collapse of Chinese resistance that Japan had hoped to achieve, instead the Chinese government relocated inland to Chongqing and continued the war.^[31]

Japanese invasion of the Soviet Union and Mongolia[link]

Soviet troops fought the Japanese during the Battle of Khalkhin Gol in Mongolia, 1939.

On 29 July 1938, the Japanese invaded the USSR and were checked at the Battle of Lake Khasan. Although the battle was a Soviet victory, the Japanese dismissed it as an inconclusive draw, and on 11 May 1939 decided to move the Japanese-Mongolian border up to the Khalkhin Gol River by force. After initial successes the Japanese assault on Mongolia was checked by the Red Army that inflicted the first major defeat on the Japanese Kwantung Army.^[32][33]

These clashes convinced some factions in the Japanese government that they should focus on conciliating the Soviet government to avoid interference in the war against China and instead turn their military attention southward, towards the US and European holdings in the Pacific, and also prevented the sacking of experienced Soviet military leaders such as Georgy Zhukov, who would later play a vital role in the defence of Moscow.^[34]

European occupations and agreements[link]

From left to right (front): Chamberlain, Daladier, Hitler, Mussolini, and Ciano pictured before signing the Munich Agreement.

In Europe, Germany and Italy were becoming bolder. In March 1938, Germany annexed Austria, again provoking little response from other European powers.^[35] Encouraged, Hitler began pressing German claims on the Sudetenland, an area of Czechoslovakia with a predominantly ethnic German population; and soon France and Britain conceded this territory to Germany in the Munich Agreement, which was made against the wishes of the Czechoslovak government, in exchange for a promise of no further territorial demands.^[36] Soon after that, however, Germany and Italy forced Czechoslovakia to cede additional territory to Hungary and Poland.^[37] In March 1939, Germany invaded the remainder of Czechoslovakia and subsequently split it into the German Protectorate of Bohemia and Moravia and the pro-German client state, the Slovak Republic.^[38]

Alarmed, and with Hitler making further demands on Danzig, France and Britain guaranteed their support for Polish independence; when Italy conquered Albania in April 1939, the same guarantee was extended to Romania and Greece.^[39] Shortly after the Franco-British pledge to Poland, Germany and Italy formalised their own alliance with the Pact of Steel.^[40]

In August 1939, Germany and the Soviet Union signed the Molotov–Ribbentrop Pact,^[41] a non-aggression treaty with a secret protocol. The parties gave each other rights, "in the event of a territorial and political rearrangement," to "spheres of influence" (western Poland and Lithuania for Germany, and eastern Poland, Finland, Estonia, Latvia and Bessarabia for the USSR). It also raised the question of continuing Polish independence.^[42]

Course of the war[link]

War breaks out in Europe[link]

Common parade of German Wehrmacht and Soviet Red Army on 23 September 1939 in Brest, Eastern Poland at the end of the Invasion of Poland. At centre is Major General Heinz Guderian and at right is Brigadier Semyon Krivoshein.

On 1 September 1939, Germany and Slovakia—a client state in 1939—attacked Poland.^[43] On 3 September France and Britain, followed by the countries of the Commonwealth,^[44] declared war on Germany but provided little support to Poland other than a small French attack into the Saarland.^[45] Britain and France also began a naval blockade of Germany on 3 September which aimed to damage the country's economy and war effort.^[46][47] On 17 September, after signing a cease-fire with Japan, the Soviets also invaded Poland.^[48] Poland's territory was divided between Germany and the Soviet Union, with Lithuania and Slovakia also receiving small shares. The Poles did not surrender; they established a Polish Underground State and an underground Home Army, and continued to fight with the Allies on all fronts outside Poland.^[49] About 100,000 Polish military personnel were evacuated to Romania and the Baltic countries; many of these soldiers later fought against the Germans in other theaters of the war.^[50] Poland's Enigma codebreakers were also evacuated to France.^[51] During this time, Japan launched its first attack against Changsha, a strategically important Chinese city, but was repulsed by late September.^[52]

Following the invasion of Poland and a German-Soviet treaty governing Lithuania, the Soviet Union forced the Baltic countries to allow it to station Soviet troops in their countries under pacts of "mutual assistance."^[53][54][55] Finland rejected territorial demands and was invaded by the Soviet Union in November 1939.^[56] The resulting conflict ended in March 1940 with Finnish concessions.^[57] France and the United Kingdom, treating the Soviet attack on Finland as tantamount to entering the war on the side of the Germans, responded to the Soviet invasion by supporting the USSR's expulsion from the League of Nations.^[55]

German troops by the Arc de Triomphe, Paris, after the 1940 fall of France.

In Western Europe, British troops deployed to the Continent, but in a phase nicknamed the Phoney War by the British and "Sitzkrieg" (sitting war) by the Germans, neither side launched major operations against the other until April 1940.^[58] The Soviet Union and Germany entered a trade pact in February 1940, pursuant to which the Soviets received German military and industrial equipment in exchange for supplying raw materials to Germany to help circumvent the Allied blockade.^[59]

In April 1940, Germany invaded Denmark and Norway to secure shipments of iron ore from Sweden, which the Allies were about to disrupt.^[60] Denmark immediately capitulated, and despite Allied support, Norway was conquered within two months.^[61] In May 1940 Britain invaded Iceland to preempt a possible German invasion of the island.^[62] British discontent over the Norwegian campaign led to the replacement of Prime Minister Neville Chamberlain with Winston Churchill on 10 May 1940.^[63]

Axis advances[link]

Germany invaded France, Belgium, the Netherlands, and Luxembourg on 10 May 1940.^[64] The Netherlands and Belgium were overrun using blitzkrieg tactics in a few days and weeks, respectively.^[65] The French fortified Maginot Line and the Allied forces in Belgium were circumvented by a flanking movement through the thickly wooded Ardennes region,^[66] mistakenly perceived by French planners as an impenetrable natural barrier against armoured vehicles.^[67] British troops were forced to evacuate the continent at Dunkirk, abandoning their heavy equipment by early June.^[68] On 10 June, Italy invaded France, declaring war on both France and the United Kingdom;^[69] twelve days later France surrendered and was soon divided into German and Italian occupation zones,^[70] and an unoccupied rump state under the Vichy Regime. On 3 July, the British attacked the French fleet in Algeria to prevent its possible seizure by Germany.^[71]

In June, during the last days of the Battle of France, the Soviet Union forcibly annexed Estonia, Latvia and Lithuania,^[54] and then annexed the disputed Romanian region of Bessarabia. Meanwhile, Nazi-Soviet political rapprochement and economic cooperation^[72][73] gradually stalled,^[74][75] and both states began preparations for war.^[76]

With France neutralized, Germany began an air superiority campaign over Britain (the Battle of Britain) to prepare for an invasion.^[77] The campaign failed, and the invasion plans were canceled by September.^[77] Using newly captured French ports, the German Navy enjoyed success against an over-extended Royal Navy, using U-boats against British shipping in the Atlantic.^[78] Italy began operations in the Mediterranean, initiating a siege of Malta in June, conquering British Somaliland in August, and making an incursion into British-held Egypt in September 1940. Japan increased its blockade of China in September by seizing several bases in the northern part of the now-isolated French Indochina.^[79]

The Battle of Britain ended the German advance in Western Europe.

Throughout this period, the neutral United States took measures to assist China and the Western Allies. In November 1939, the American Neutrality Act was amended to allow "cash and carry" purchases by the Allies.^[80] In 1940, following the German capture of Paris, the size of the United States Navy was significantly increased and, after the Japanese incursion into Indochina, the United States embargoed iron, steel and mechanical parts against Japan.^[81] In September, the United States further agreed to a trade of American destroyers for British bases.^[82] Still, a large majority of the American public continued to oppose any direct military intervention into the conflict well into 1941.^[83]

At the end of September 1940, the Tripartite Pact united Japan, Italy and Germany to formalize the Axis Powers.^[84] The Tripartite Pact stipulated that any country, with the exception of the Soviet Union, not in the war which attacked any Axis Power would be forced to go to war against all three.^[85] During this time, the United States continued to support the United Kingdom and China by introducing the Lend-Lease policy authorizing the provision of materiel and other items^[86] and creating a security zone spanning roughly half of the Atlantic Ocean where the United States Navy protected British convoys.^[87] As a result, Germany and the United States found themselves engaged in sustained naval warfare in the North and Central Atlantic by October 1941, even though the United States remained officially neutral.^[88][89]

The Axis expanded in November 1940 when Hungary, Slovakia and Romania joined the Tripartite Pact.^[90] In October 1940, Italy invaded Greece but within days was repulsed and pushed back into Albania, where a stalemate soon occurred.^[91] In December 1940, British Commonwealth forces began counter-offensives against Italian forces in Egypt and Italian East Africa.^[92] By early 1941, with Italian forces having been pushed back into Libya by the Commonwealth, Churchill ordered a dispatch of troops from Africa to bolster the Greeks.^[93] The Italian Navy also suffered significant defeats, with the Royal Navy putting three Italian battleships out of commission by a carrier attack at Taranto, and neutralising several more warships at the Battle of Cape Matapan.^[94]

German paratroopers invading the Greek island of Crete, May 1941.

The Germans soon intervened to assist Italy. Hitler sent German forces to Libya in February, and by the end of March they had launched an offensive against the diminished Commonwealth forces.^[95] In under a month, Commonwealth forces were pushed back into Egypt with the exception of the besieged port of Tobruk.^[96] The Commonwealth attempted to dislodge Axis forces in May and again in June, but failed on both occasions.^[97] In early April, following Bulgaria's signing of the Tripartite Pact, the Germans intervened in the Balkans by invading Greece and Yugoslavia following a coup; here too they made rapid progress, eventually forcing the Allies to evacuate after Germany conquered the Greek island of Crete by the end of May.^[98]

The Allies did have some successes during this time. In the Middle East, Commonwealth forces first quashed a coup in Iraq which had been supported by German aircraft from bases within Vichy-controlled Syria,^[99] then, with the assistance of the Free French, invaded Syria and Lebanon to prevent further such occurrences.^[100] In the Atlantic, the British scored a much-needed public morale boost by sinking the German flagship Bismarck.^[101] Perhaps most importantly, during the Battle of Britain the Royal Air Force had successfully resisted the Luftwaffe's assault, and the German bombing campaign largely ended in May 1941.^[102]

In Asia, despite several offensives by both sides, the war between China and Japan was stalemated by 1940. In order to increase pressure on China by blocking supply routes, and to better position Japanese forces in the event of a war with the Western powers, Japan had seized military control of southern Indochina^[103] In August of that year, Chinese communists launched an offensive in Central China; in retaliation, Japan instituted harsh measures (the Three Alls Policy) in occupied areas to reduce human and material resources for the communists.^[104] Continued antipathy between Chinese communist and nationalist forces culminated in armed clashes in January 1941, effectively ending their co-operation.^[105] With the situation in Europe and Asia relatively stable, Germany, Japan, and the Soviet Union made preparations. With the Soviets wary of mounting tensions with Germany and the Japanese planning to take advantage of the European War by seizing resource-rich European possessions in Southeast Asia, the two powers signed the Soviet–Japanese Neutrality Pact in April 1941.^[106] By contrast, the Germans were steadily making preparations for an attack on the Soviet Union, amassing forces on the Soviet border.^[107]

The war becomes global[link]

German infantry and armoured vehicles battle the Soviet defenders on the streets of Kharkov, October 1941.

On 22 June 1941, Germany, along with other European Axis members and Finland, invaded the Soviet Union in Operation Barbarossa. The primary targets of this surprise offensive^[108] were the Baltic region, Moscow and Ukraine, with an ultimate goal of ending the 1941 campaign near the Arkhangelsk-Astrakhan line, connecting the Caspian and White Seas. Hitler's objectives were to eliminate the Soviet Union as a military power, exterminate Communism, generate Lebensraum ("living space")^[109] by dispossessing the native population^[110] and guarantee access to the strategic resources needed to defeat Germany's remaining rivals.^[111]

Although the Red Army was preparing for strategic counter-offensives before the war,^[112] Barbarossa forced the Soviet supreme command to adopt a strategic defence. During the summer, the Axis made significant gains into Soviet territory, inflicting immense losses in both personnel and materiel. By the middle of August, however, the German Army High Command decided to suspend the offensive of a considerably depleted Army Group Centre, and to divert the 2nd Panzer Group to reinforce troops advancing towards central Ukraine and Leningrad.^[113] The Kiev offensive was overwhelmingly successful, resulting in encirclement and elimination of four Soviet armies, and made further advance into Crimea and industrially developed Eastern Ukraine (the First Battle of Kharkov) possible.^[114]

Soviet counter-attack during the battle of Moscow, December, 1941.

The diversion of three quarters of the Axis troops and the majority of their air forces from France and the central Mediterranean to the Eastern Front^[115] prompted Britain to reconsider its grand strategy.^[116] In July, the UK and the Soviet Union formed a military alliance against Germany^[117] The British and Soviets invaded Iran to secure the Persian Corridor and Iran's oil fields.^[118] In August, the United Kingdom and the United States jointly issued the Atlantic Charter.^[119]

Romania made the largest contribution to recapture territory ceded to the USSR and pursue its leader Ion Antonescu's desire to combat communism.^[120] By October, when Axis operational objectives in Ukraine and the Baltic region were achieved, with only the sieges of Leningrad^[121] and Sevastopol continuing,^[122] a major offensive against Moscow had been renewed. After two months of fierce battles, the German army almost reached the outer suburbs of Moscow, where the exhausted troops^[123] were forced to suspend their offensive.^[124] Large territorial gains were made by Axis forces, but their campaign had failed to achieve its main objectives: two key cities remained in Soviet hands, the Soviet capability to resist was not broken, and the Soviet Union retained a considerable part of its military potential. The blitzkrieg phase of the war in Europe had ended.^[125]

The Axis-controlled territory in Europe at the time of its maximal expansion (1941–42).

By early December, freshly mobilised reserves^[126] allowed the Soviets to achieve numerical parity with Axis troops.^[127] This, as well as intelligence data that established a minimal number of Soviet troops in the East sufficient to prevent any attack by the Japanese Kwantung Army,^[128] allowed the Soviets to begin a massive counter-offensive that started on 5 December along a 1,000 kilometres (620 mi) front and pushed German troops 100–250 kilometres (62–160 mi) west.^[129]