APO 339 MAASTRICHT, HOLLAND DUTCH WWII 1945 Army Cover 252 ENGR (C) Bn APO 647

It was canceled "APO" 8 Jan 1945. It is franked with stamp "Air Mail". It was sent from Paul Kunkle to Alliance, OH.

This cover is in good condition. Please look at the scan and make your own judgement. 

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World War II (WWII or WW2), also known as the Second World War, was a global war that lasted from 1939 to 1945, though related conflicts began earlier. It involved the 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, and directly involved more than 100 million people, from more than 30 different countries. In a state of "total war", the major participants threw their entire economic, industrial, and scientificcapabilities behind the war effort, erasing the distinction between civilian and military resources. Marked by mass deaths of civilians, including the Holocaust, the Three Alls Policy, the strategic bombing of enemy industrial and/or population centres, and the first use of nuclear weapons in combat, it resulted in an estimated50 million to 85 million fatalities. These made World War II the deadliest conflict in human history.^[1]

The Empire of Japan aimed to dominate Asia and the Pacific and was already at war with the Republic of Chinain 1937,^[2] but the world war is generally said to have begun on 1 September 1939 with the invasion of Polandby Germany and subsequent declarations of war on Germany by France and the United Kingdom. From late 1939 to early 1941, in a series of campaigns and treaties, Germany formed the Axis alliance with Italy andJapan, conquering or subduing much of continental Europe. Following the Molotov–Ribbentrop Pact, Germany and the Soviet Union partitioned between themselves and annexed territories of their European neighbours,including Poland, Finland and the Baltic states. The United Kingdom and the other members of the British Commonwealth were the only major Allied forces continuing the fight against the Axis, with battles taking place inNorth Africa and the Horn of Africa as well as the long-running Battle of the Atlantic. In June 1941, the European Axis powers 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 for the rest of the war. In December 1941, Japanattacked the United States and European territories in the Pacific Ocean, and quickly conquered much of the Western Pacific.

The Axis advance was stopped in 1942 when Japan lost a critical Battle of Midway, near Hawaii, and Germany was defeated in North Africa and then, decisively, at Stalingrad in the Soviet Union. In 1943, with a series of German defeats on the Eastern Front, the Allied invasion of Italy which brought about that nation's surrender, and Allied 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. During 1944 and 1945 the Japanese began suffering major reverses in mainland Asia inSouth Central China and Burma, while the Allies defeated the Japanese Navy and captured key Western Pacific islands.

The war in Europe ended with an invasion of Germany by the Western Allies and the Soviet Union culminating in the capture of Berlin by Soviet and Polish troops and the subsequent German unconditional surrender on 8 May 1945. Following the Potsdam Declaration by the Allies on 26 July 1945, the United States dropped atomic bombs on the Japanese cities of Hiroshima and Nagasaki on 6 August and 9 August respectively. With aninvasion of the Japanese archipelago imminent, the possibility of additional atomic bombings, and the Soviet Union's declaration of war on Japan and invasion of Manchuria, Japan surrendered on 15 August 1945. Thus ended the war in Asia, cementing the total victory of the Allies over the Axis.

World War II altered the political alignment and social structure of the world. The United Nations (UN) was established to foster international co-operation and prevent future conflicts. The great powers that were the victors of the war—the United States, the Soviet Union, China, the United Kingdom, and France—became thepermanent members of the United Nations 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 and co-operate more effectively in the Cold War.^[4]

Chronology

The start of the war in Europe 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. The dates for the beginning of war in the Pacific include the start of the Second Sino-Japanese War on 7 July 1937,^[5] or even the Japanese invasion of Manchuria on 19 September 1931.

Others follow the 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 British historian Antony Beevor views the beginning of the Second World War as theBattles of Khalkhin Gol fought between Japan and the forces of Mongolia and the Soviet Union from May to September 1939.^[7]

The exact date of the war's end is also not universally agreed upon. It was generally accepted at the time that the war ended with the armistice of 14 August 1945 (V-J Day), rather than the formal surrender of Japan (2 September 1945); it is even claimed in some European histories that it ended on V-E Day (8 May 1945).^{[citation needed]} A peace treaty with Japan was signed in 1951 to formally tie up any loose ends such as compensation to be paid to Allied prisoners of war who had been victims of atrocities.^[8] A treaty regarding Germany's future allowed the reunification of East and West Germany to take place in 1990 and resolved other post-World War II issues.^[9]

Background

World War I had 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, whereas new states were created out of the collapse of Austria-Hungary and the Ottoman and Russian Empires.

To prevent the outbreak of a future world war, the League of Nations was formally created during the 1919 Paris Peace Conference. The organisation's primary goal was to prevent armed conflict through collective security, military and naval disarmament, and settling international disputes through peaceful negotiations and arbitration.

Despite strong pacifist sentiment after World War I,^[10] its aftermath still caused irredentist and revanchist nationalism to become 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.^[11] Meanwhile, the Russian Civil War had led to the creation of the Soviet Union.^[12]

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 collaborationistagenda 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, promising the creation of a "New Roman Empire".^[13]

The League of Nations assembly, held in Geneva, Switzerland, 1930

In Germany, the Weimar Republic's legitimacy was challenged by right-wing elements such as the Freikorps and the Nazi party, resulting in events such as the Kapp Putsch and the Beer Hall Putsch. With the onset of the Great Depression in 1929, domestic support for Nazism and its leader Adolf Hitler rose and, in 1933, he was appointed Chancellor of Germany. In the aftermath of the Reichstag fire, Hitler created a totalitarian single-party state led by the Nazis.^[14]

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.^[15] In 1931, anincreasingly militaristic Japanese Empire, which had long sought influence in China^[16] 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.^[17]

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.^[18]

Adolf Hitler at a German National Socialist political rally in Weimar, October 1930

Adolf Hitler, after an unsuccessful attempt to overthrow the German government in 1923, eventually 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.^[19] It was at this time that multiple political scientists began to predict that a second Great War might take place.^[20] 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.^[21]

Hoping to contain Germany, the United Kingdom, France and Italy formed the Stresa Front; however, in June 1935, the United Kingdom made an independent naval agreement with Germany, easing prior restrictions. 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.^[22] The United States, concerned with events in Europe and Asia, passed the Neutrality Act in August.^[23] In October, Italy invaded Ethiopia through Italian Somaliland and Eritrea;^[24] Germany was the only major European nation to support the invasion. Italy subsequently dropped its objections to Germany's goal of absorbing Austria.^[25]

Hitler defied the Versailles and Locarno treaties by remilitarising the Rhineland in March 1936. He received little response from other European powers.^[26] When theSpanish Civil War broke out in July, Hitler and Mussolini supported the fascist and authoritarian Nationalist forces in their civil war against the Soviet-supportedSpanish Republic. Both sides used the conflict to test new weapons and methods of warfare,^[27] 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 to present a united front to oppose Japan.^[28]

Pre-war events

Italian invasion of Ethiopia (1935)

Italian soldiers recruited in 1935, on their way to fight the Second Italo-Abyssinian War

The Second Italo–Abyssinian War was a brief colonial war that began in October 1935 and ended in May 1936. The war began with the invasion of the Ethiopian Empire (also known as Abyssinia) by the armed forces of the Kingdom of Italy(Regno d'Italia), which was launched from Italian Somaliland and Eritrea.^[24] 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.^[29]

Spanish Civil War (1936–39)

The bombing of Guernica in 1937, sparked Europe-wide fears that the next war would be based on bombing of cities with very high civilian casualties

During the Spanish Civil War, Hitler and Mussolini lent military support to theNationalist rebels, led by General Francisco Franco. The Soviet Union supported the existing government, the Spanish Republic. Over 30,000 foreign volunteers, known as the International Brigades, also fought against the Nationalists. Both Germany and the USSR used this proxy war as an opportunity to test in combat their most advanced weapons and tactics. The bombing of Guernica by the German Condor Legion in April 1937 heightened widespread concerns that the next major war would include extensive terror bombing attacks on civilians.^[30][31] The Nationalists won the civil war in April 1939; Franco, now dictator, bargained with both sides during the Second World War, but never concluded any major agreements. He did send volunteers to fight on the eastern front under German command but Spain remained neutral and did not allow either side to use its territory.^[32]

Japanese invasion of China (1937)

Japanese Imperial Army soldiers during 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.^[33] The Soviets quickly signed a non-aggression pact with China to lend materiel support, effectively ending China's prior co-operation 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. After the fall of Nanking, tens of thousands if not hundreds of thousands of Chinese civilians and disarmed combatants weremurdered by the Japanese.^[34][35]

In March 1938, Nationalist Chinese force got their first major victory at Taierzhuang but then city Xuzhou was taken by Japanese in May.^[36] In June 1938, Chinese forces stalled the Japanese advance by flooding the Yellow River; this manoeuvre bought time for the Chinese to prepare their defences at Wuhan, but the city was taken by October.^[37] Japanese military victories did not bring about the collapse of Chinese resistance that Japan had hoped to achieve; instead the Chinese government relocated inland toChongqing and continued the war.^[38][39]

Japanese invasion of the Soviet Union and Mongolia (1938)

Japanese forces in Manchuoko had sporadic border clashes with the Soviet Union, culminating in the Japanese defeat at Khalkin Gol. After this, Japan and the Soviet Union signed a Neutrality Pact in April 1941, and Japan turned its focus to the South Pacific.

European occupations and agreements

Chamberlain, Daladier, Hitler,Mussolini, and Ciano pictured just before signing the Munich Agreement, 29 September 1938

In Europe, Germany and Italy were becoming more bold. In March 1938, Germany annexed Austria, again provoking little response from other European powers.^[40] Encouraged, Hitler began pressing German claims on the Sudetenland, an area of Czechoslovakia with a predominantly ethnic German population; and soon Britain and France followed the counsel of prime minister Neville Chamberlain and 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.^[41] Soon afterwards, Germany and Italy forced Czechoslovakia to cede additional territory to Hungary and Poland.^[42]

Although all of Germany's stated demands had been satisfied by the agreement, privately Hitler was furious that British interference had prevented him from seizing all of Czechoslovakia in one operation. In subsequent speeches Hitler attacked British and Jewish "war-mongers" and in January 1939 secretly ordered a major build-up of the German navy to challenge British naval supremacy. In March 1939, Germany invaded the remainder of Czechoslovakia and subsequently split it into the German Protectorate of Bohemia and Moravia and a pro-German client state, the Slovak Republic.^[43] Hitler also delivered an ultimatum to Lithuania, forcing the concession of the Klaipėda Region.

German Foreign MinisterRibbentrop signing the Nazi–Soviet non-aggression pact. Standing behind him are Molotov and the Soviet leaderJoseph Stalin, 1939

Alarmed, and with Hitler making further demands on the Free City of Danzig, France and Britain guaranteed their support for Polish independence; when Italy conquered Albania in April 1939, the same guarantee was extended to Romania andGreece.^[44] Shortly after the Franco-British pledge to Poland, Germany and Italy formalised their own alliance with the Pact of Steel.^[45] Hitler accused Britain and Poland of trying to "encircle" Germany and renounced the Anglo-German Naval Agreement and the German–Polish Non-Aggression Pact.

In August 1939, Germany and the Soviet Union signed the Molotov–Ribbentrop Pact,^[46] a non-aggression treaty with a secret protocol. The parties gave each other rights to "spheres of influence" (western Poland and Lithuania for Germany;eastern Poland, Finland, Estonia, Latvia and Bessarabia for the USSR). It also raised the question of continuing Polish independence.^[47] The agreement was crucial to Hitler because it assured that Germany would not have to face the prospect of a two-front war, as it had in World War I, after it defeated Poland.

The situation reached a general crisis in late August as German troops continued to mobilise against the Polish border. In a private meeting with the Italian foreign minister, Count Ciano, Hitler asserted that Poland was a "doubtful neutral" that needed to either yield to his demands or be "liquidated" to prevent it from drawing off German troops in the future "unavoidable" war with the Western democracies. He did not believe Britain or France would intervene in the conflict.^[48] On 23 August Hitler ordered the attack to proceed on 26 August, but upon hearing that Britain had concluded a formal mutual assistance pact with Poland and that Italy would maintain neutrality, he decided to delay it.^[49] In response to British pleas for direct negotiations, Germany demanded on 29 August that a Polish plenipotentiary immediately travel to Berlin to negotiate the handover of Danzig and the Polish Corridor to Germany as well as to agree to safeguard the German minority in Poland. The Poles refused to comply with this request and on the evening of 31 August Germany declared that it considered its proposals rejected.^[50]

Course of the war

War breaks out in Europe (1939–40)

Soldiers of the German Wehrmachttearing down the border crossing between Poland and the Free City of Danzig, 1 September 1939

On 1 September 1939, Germany invaded Poland under the false pretext that the Poles had carried out a series of sabotage operations against German targets.^[51] Subsequently, two days later on 3 September, France and United Kingdom, followed by the fully independent Dominions^[52] of the British Commonwealth^[53] – Australia, Canada, New Zealand and South Africa – declared war on Germany. However, initially the alliance provided limited direct military support to Poland, consisting of asmall French attack into the Saarland.^[54] The Western Allies also began a naval blockade of Germany, which aimed to damage the country's economy and war effort.^[55] Germany responded by ordering U-boat warfare against Allied merchant and war ships, which was to later escalate in the Battle of the Atlantic.

German Panzer I tanks near the city of Bydgoszcz, during the Invasion of Poland, September 1939

On 17 September 1939, after signing a cease-fire with Japan, the Soviets also invaded Poland from the east.^[56] The Polish army was defeated and Warsaw surrendered to the Germans on 27 September, with final pockets of resistance surrendering on 6 October. Poland's territory was divided between Germany and theSoviet Union, with Lithuania and Slovakia also receiving small shares. After the surrender of Poland's armed forces, Polish resistance established an Underground State, a partisan Home Army, andcontinued to fight alongside the Allies on all fronts in Europe and North Africa, throughout the entire course of the war.^[57]

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 theatres of the war.^[58] Poland's Enigma codebreakers were also evacuated to France.^[59]

On 6 October Hitler made a public peace overture to the United Kingdom and France, but said that the future of Poland was to be determined exclusively by Germany and the Soviet Union. Chamberlain rejected this on 12 October, saying "Past experience has shown that no reliance can be placed upon the promises of the present German Government."^[50] After this rejection Hitler ordered an immediate offensive against France,^[60] but bad weather forced repeated postponements until the spring of 1940.^[61][62][63]

After signing the 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."^[64][65][66] Finland rejected territorial demands, prompting a Soviet invasion in November 1939.^[67] The resulting Winter War ended in March 1940 with Finnish concessions.^[68] The United Kingdom and France treating the Soviet attack on Finland as tantamount to its 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.^[66]

Western Europe (1940–41)

Map of the French Maginot Line

View of London after the German"Blitz", 29 December 1940

In April 1940, Germany invaded Denmark and Norway to protect shipments of iron ore from Sweden, which the Allies were attempting to cut off by unilaterally mining neutral Norwegian waters.^[69] Denmark capitulated after a few hours, and despite Allied support, during which the important harbour of Narvik temporarily was recaptured by the British, Norway was conquered within two months.^[70] British discontent over the Norwegian campaign led to the replacement of the British Prime Minister, Neville Chamberlain, with Winston Churchill on 10 May 1940.^[71]

Germany launched an offensive against France and, for reasons of military strategy, also attacked the neutral nations of Belgium, the Netherlands, and Luxembourg on 10 May 1940.^[72] That same day the United Kingdom occupied the Danish possessions of Iceland, Greenland and the Faroes to preempt a possible German invasion of the islands.^[73] The Netherlands and Belgium were overrun using blitzkriegtactics in a few days and weeks, respectively.^[74] The French-fortified Maginot Line and the main body the Allied forces which had moved into Belgium were circumvented by a flanking movement through the thickly wooded Ardennes region,^[75] mistakenly perceived by Allied planners as an impenetrable natural barrier against armoured vehicles.^[76] As a result, the bulk of the Allied armies found themselves trapped in an encirclement and were beaten. The majority were taken prisoner, whilst over 300,000, mostly British and French, were evacuated from the continent at Dunkirk by early June, although abandoning almost all of their equipment.^[77]

On 10 June, Italy invaded France, declaring war on both France and the United Kingdom.^[78] Paris fell to the Germans on 14 June and eight days later France surrendered and was soon divided into German and Italian occupation zones,^[79] and an unoccupied rump state under the Vichy Regime, which, though officially neutral, was generally aligned with Germany. France kept its fleet but the British feared the Germans would seize it, so on 3 July, the British attacked it.^[80]

In June 1940, the Soviet Union forcibly annexed Estonia, Latvia and Lithuania,^[65] and then annexed the disputed Romanian region of Bessarabia. Meanwhile, Nazi-Soviet political rapprochement and economic co-operation^[81][82] gradually stalled,^[83][84] and both states began preparations for war.^[85]

On 19 July, Hitler again publicly offered to end the war, saying he had no desire to destroy the British Empire. The United Kingdom rejected this, with Lord Halifax responding "there was in his speech no suggestion that peace must be based on justice, no word of recognition that the other nations of Europe had any right to self‑determination ..."^[86]

Following this, Germany began an air superiority campaign over the United Kingdom (the Battle of Britain) to prepare for an invasion.^[87] The campaign failed, and the invasion plans were cancelled by September.^[87] Frustrated, and in part in response to repeated British air raids against Berlin, Germany began a strategic bombing offensive against British cities known as the Blitz.^[88] However, the air attacks largely failed to disrupt the British war effort.

German Luftwaffe, Heinkel He 111bombers during the Battle of Britain

Using newly captured French ports, the German Navy enjoyed success against an over-extended Royal Navy, using U-boatsagainst British shipping in the Atlantic.^[89] The British scored a significant victory on 27 May 1941 by sinking the German battleship Bismarck.^[90] 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.^[91]

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.^[92] In 1940, following the German capture of Paris, the size of the United States Navy was significantly increased. In September, the United States further agreed to a trade of American destroyers for British bases.^[93] Still, a large majority of the American public continued to oppose any direct military intervention into the conflict well into 1941.^[94]

Although Roosevelt had promised to keep the United States out of the war, he nevertheless took concrete steps to prepare for that eventuality. In December 1940 he accused Hitler of planning world conquest and ruled out negotiations as useless, calling for the US to become an "arsenal for democracy" and promoted the passage of Lend-Lease aid to support the British war effort.^[86] In January 1941 secret high level staff talks with the British began for the purposes of determining how to defeat Germany should the US enter the war. They decided on a number of offensive policies, including an air offensive, the "early elimination" of Italy, raids, support of resistance groups, and the capture of positions to launch an offensive against Germany.^[95]

At the end of September 1940, the Tripartite Pact united Japan, Italy and Germany to formalise the Axis Powers. 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.^[96] The Axis expanded in November 1940 when Hungary, Slovakia and Romania joined the Tripartite Pact.^[97] Romania would make a major contribution (as did Hungary) to the Axis war against the USSR, partially to recapture territory ceded to the USSR, partially to pursue its leader Ion Antonescu's desire to combat communism.^[98]

Mediterranean (1940–41)

Australian troops of the British Commonwealth Forces man a front-line trench during the Siege of Tobruk;North African Campaign, August 1941

Italy began operations in the Mediterranean, initiating a siege of Malta in June, conquering British Somaliland in August, andmaking an incursion into British-held Egypt in September 1940. In October 1940, Italy started the Greco-Italian War due to Mussolini's jealousy of Hitler's success but within days was repulsed and pushed back into Albania, where a stalemate soon occurred.^[99] The United Kingdom responded to Greek requests for assistance by sending troops to Crete and providing air support to Greece. Hitler decided that when the weather improved he would take action against Greece to assist the Italians and prevent the British from gaining a foothold in the Balkans, to strike against the British naval dominance of the Mediterranean, and to secure his hold on Romanian oil.^[100]

In December 1940, British Commonwealth forces began counter-offensives against Italian forces in Egypt and Italian East Africa.^[101] The offensive in North Africa was highly successful and by early February 1941 Italy had lost control of eastern Libya and large numbers of Italian troops had been taken prisoner. 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.^[102]

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 which drove back the Commonwealth forces which had been weakened to support Greece.^[103] In under a month, Commonwealth forces were pushed back into Egypt with the exception of the besieged port of Tobruk.^[104]The Commonwealth attempted to dislodge Axis forces in May and again in June, but failed on both occasions.^[105]

By late March 1941, following Bulgaria's signing of the Tripartite Pact, the Germans were in position to intervene in Greece. Plans were changed, however, due to developments in neighbouring Yugoslavia. The Yugoslav government had signed the Tripartite Pact on 25 March, only to be overthrown two days later by a British-encouraged coup. Hitler viewed the new regime as hostile and immediately decided to eliminate it. On 6 April Germany simultaneously invaded both Yugoslavia andGreece, making rapid progress and forcing both nations to surrender within the month. The British were driven from the Balkans after Germany conquered the Greek island of Crete by the end of May.^[106] Although the Axis victory was swift, bitter partisan warfare subsequently broke out against the Axis occupation of Yugoslavia, which continued until the end of the war.

The Allies did have some successes during this time. In the Middle East, Commonwealth forces first quashed an uprising in Iraq which had been supported by German aircraft from bases within Vichy-controlled Syria,^[107] then, with the assistance of the Free French, invaded Syria and Lebanon to prevent further such occurrences.^[108]

Axis attack on the USSR (1941)

Animation of the WWII European Theatre

Soviet civilians in Leningrad leaving destroyed houses, after a German bombardment of the city; Battle of Leningrad, 10 December 1942

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.^[109] By contrast, the Germans were steadily making preparations for an attack on the Soviet Union, amassing forces on the Soviet border.^[110]

Hitler believed that Britain's refusal to end the war was based on the hope that the United States and the Soviet Union would enter the war against Germany sooner or later.^[111] He accordingly decided to try to strengthen Germany's relations with the Soviets, or failing that, to attack and eliminate them as a factor. In November 1940 negotiations took place to determine if the Soviet Union would join the Tripartite Pact. The Soviets showed some interest, but asked for concessions from Finland, Bulgaria, Turkey, and Japan that Germany considered unacceptable. On 18 December 1940 Hitler issued the directive to prepare for an invasion of the Soviet Union.

On 22 June 1941, Germany, supported by Italy and Romania, invaded the Soviet Union in Operation Barbarossa, with Germany accusing the Soviets of plotting against them. They were joined shortly by Finland and Hungary.^[112] The primary targets of this surprise offensive^[113] were the Baltic region, Moscow and Ukraine, with the ultimate goal of ending the 1941 campaign near the Arkhangelsk-Astrakhan line, from the Caspian to the White Seas. Hitler's objectives were to eliminate the Soviet Union as a military power, exterminate Communism, generate Lebensraum ("living space")^[114] bydispossessing the native population^[115] and guarantee access to the strategic resources needed to defeat Germany's remaining rivals.^[116]

Although the Red Army was preparing for strategic counter-offensives before the war,^[117] 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 Commanddecided 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.^[118] 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.^[119]

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^[120] prompted Britain to reconsider its grand strategy.^[121] In July, the UK and the Soviet Union formed a military alliance against Germany^[122] The British and Soviets invaded Iranto secure the Persian Corridor and Iran's oil fields.^[123] In August, the United Kingdom and the United States jointly issued the Atlantic Charter.^[124]

By October Axis operational objectives in Ukraine and the Baltic region were achieved, with only the sieges of Leningrad^[125] and Sevastopol continuing.^[126] A majoroffensive against Moscow was renewed; after two months of fierce battles in increasingly harsh weather the German army almost reached the outer suburbs of Moscow, where the exhausted troops^[127] were forced to suspend their offensive.^[128] 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.^[129]

By early December, freshly mobilised reserves^[130] allowed the Soviets to achieve numerical parity with Axis troops.^[131] This, as well as intelligence data which established that a minimal number of Soviet troops in the East would be sufficient to deter any attack by the Japanese Kwantung Army,^[132] allowed the Soviets to begin a massive counter-offensive that started on 5 December all along the front and pushed German troops 100–250 kilometres (62–155 mi) west.^[133]

War breaks out in the Pacific (1941)

Mitsubishi A6M2, "Zero" fighters on the Imperial Japanese Navy aircraft carrier Shōkaku, just before the attack on Pearl Harbor

In 1939 the United States had renounced its trade treaty with Japan and beginning with an aviation gasoline ban in July 1940 Japan had become subject to increasing economic pressure.^[86] During this time, Japan launched its first attack against Changsha, a strategically important Chinese city, but was repulsed by late September.^[134] Despite several offensives by both sides, the war between China and Japan was stalemated by 1940. 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 occupied northern Indochina.^[135] Afterwards, the United States embargoed iron, steel and mechanical parts against Japan.^[136] Other sanctions soon followed.

In August of that year, Chinese communists launched an offensive in Central China; in retaliation, Japan instituted harsh measures in occupied areas to reduce human and material resources for the communists.^[137] Continued antipathy between Chinese communist and nationalist forces culminated in armed clashes in January 1941, effectively ending their co-operation.^[138] In March, the Japanese 11th army attacked the headquarters of the Chinese 19th army but was repulsed during Battle of Shanggao.^[139] In September, Japan attempted to take the city of Changsha again and clashed with Chinese nationalist forces.^[140]

German successes in Europe encouraged Japan to increase pressure on European governments in Southeast Asia. The Dutch government agreed to provide Japan some oil supplies from the Dutch East Indies, but negotiations for additional access to their resources ended in failure in June 1941.^[141] In July 1941 Japan sent troops to southern Indochina, thus threatening British and Dutch possessions in the Far East. The United States, United Kingdom and other Western governments reacted to this move with a freeze on Japanese assets and a total oil embargo.^[142][143]

Since early 1941 the United States and Japan had been engaged in negotiations in an attempt to improve their strained relations and end the war in China. During these negotiations Japan advanced a number of proposals which were dismissed by the Americans as inadequate.^[144] At the same time the US, Britain, and the Netherlands engaged in secret discussions for the joint defence of their territories, in the event of a Japanese attack against any of them.^[145] Roosevelt reinforcedthe Philippines (an American possession since 1898) and warned Japan that the US would react to Japanese attacks against any "neighboring countries".^[145]

USS Arizona during the Japanese surprise air attack on the American pacific fleet, 7 December 1941

Frustrated at the lack of progress and feeling the pinch of the American-British-Dutch sanctions, Japan prepared for war. On 20 November it presented an interim proposal as its final offer. It called for the end of American aid to China and the supply of oil and other resources to Japan. In exchange they promised not to launch any attacks in Southeast Asia and to withdraw their forces from their threatening positions in southern Indochina.^[144] The American counter-proposal of 26 November required that Japan evacuate all of China without conditions and conclude non-aggression pacts with all Pacific powers.^[146]That meant Japan was essentially forced to choose between abandoning its ambitions in China, or seizing the natural resources it needed in the Dutch East Indies by force;^[147] the Japanese military did not consider the former an option, and many officers considered the oil embargo an unspoken declaration of war.^[148]

Japan planned to rapidly seize European colonies in Asia to create a large defensive perimeter stretching into the Central Pacific; the Japanese would then be free to exploit the resources of Southeast Asia while exhausting the over-stretched Allies by fighting a defensive war.^[149] To prevent American intervention while securing the perimeter it was further planned to neutralise the United States Pacific Fleet and the American military presence in the Philippines from the outset.^[150] On 7 December (8 December in Asian time zones), 1941, Japan attacked British and American holdings with near-simultaneous offensives against Southeast Asia and the Central Pacific.^[151] These included an attack on the American fleet at Pearl Harbor, landings in Thailand and Malaya^[151] and the battle of Hong Kong.

These attacks led the United States, Britain, China, Australia and several other states to formally declare war on Japan, whereas the Soviet Union, being heavily involved in large-scale hostilities with European Axis countries, preferred to maintain its neutrality agreement with Japan.^[152] Germany, followed by the other Axis states, declared war on the United States in solidarity with Japan, citing as justification the American attacks on German submarines and merchant ships that had been ordered by Roosevelt.^[112]