The European theatre of World War II, lasting from September 1939 to May 1945, was one of two main theatres of combat during World War II, the other being the Pacific War. The combat in Europe resulted in at least 39 million deaths, and a dramatic change in the balance of power on the continent. The Allied powers, including (for most of the war) the United Kingdom, United States, Soviet Union, and France, fought the Axis powers, including the fascist states of Nazi Germany and Italy, on multiple fronts: Western, Eastern, Scandinavian, and Mediterranean. Germany, meanwhile, enacted the Holocaust, a genocide of six million Jews, within its vast occupied territories across Europe. In 1938, German dictator Adolf Hitler had his country annex Austria and part of Czechoslovakia; this was motivated in part by the Nazi Party's racist ideology, which held that Germany needed to gain "living space" for its so-called "Aryan race" to survive. The country was supported by Italy, led by dictator Benito Mussolini. World War II began with Germany's invasion of Poland on 1 September 1939. Poland's allies, France and the U.K., declared war on Germany days later, but were unwilling to engage in active combat. The Soviet Union, led by Joseph Stalin, soon invaded eastern Poland, having signed a non-aggression pact with Germany. Poland was subsequently partitioned into Soviet and German occupied territories. In 1940, Germany invaded Norway, Denmark, France, the Netherlands, Belgium, and Luxembourg, and Italy invaded Greece. Germany also began the Battle of Britain and the Blitz, two aerial bombardments of the U.K. The British prime minister was Winston Churchill. In 1941, Germany invaded Yugoslavia and Greece, and began invading the Soviet Union, which brought the Soviets into the Allied war effort. Later that year, Germany declared war on the U.S., who also joined the Allies. The U.S. president was Franklin D. Roosevelt. In 1942 and 1943, the Soviets halted the German invasion of their country at the Battle of Stalingrad, while the Allies bombed German industrial facilities. In 1943, the Allied powers began invading Italy, leading to the end of Mussolini's regime. Germans and Italians loyal to the Axis continued fighting the Allies. In 1944, the Allies liberated Rome, then began invading German-occupied Western Europe, starting with Normandy in northern France. Meanwhile, the Soviets launched a massive counteroffensive in Eastern Europe. Both campaigns were successful. The concentration camps used in the Holocaust were liberated, and the Soviets surrounded the German capital Berlin. In April 1945, Mussolini was hanged, Roosevelt died of poor health and was succeeded by Harry S. Truman, and Hitler died by suicide in response to the encirclement of Berlin. Germany unconditionally surrendered on 8 May—now celebrated as 'Victory in Europe Day'—although fighting continued in other parts of Europe until 25 May. On 5 June, Germany signed the Berlin Declaration, proclaiming its unconditional surrender to the Allies. The Allies then turned their attention to finishing the Pacific War against the Axis power of Japan. After World War II ended, the Allies occupied much of Europe. They restored countries' pre-war governments, or established new ones, and funded much of Europe's economic recovery. German military leaders were prosecuted in the Nuremberg trials. Western Europe became a bloc of capitalist governments, while Eastern Europe became communist, marking the beginning of the Cold War among the former Allied nations.
Background
Axis powers
Germany was defeated in World War I, and the 1919 Treaty of Versailles placed punitive conditions on the country after finding Germany and the other Central Powers guilty for starting the war. These punishments included the loss of Alsace-Lorraine, the temporary loss of the Saarland, military limitations, and reparation payments to the Allied powers. The Rhineland region of Germany was also made a demilitarised zone. Germany would also join the League of Nations, an international governmental body devoted to peacekeeping. Historians are divided on whether or not the treaty was harsh or actually "very restrained" compared to other peace treaties at the time. Many Germans back then blamed their country's post-war economic collapse on the treaty's conditions and these resentments contributed to the political instability, which made it possible for Adolf Hitler and his Nazi Party to come to power. This was worsened by the worldwide Great Depression, which began in 1929. Hitler became the chancellor and fuhrer of Germany in 1933. In February 1933, the German Reichstag building caught on fire in an arson attack, giving Hitler the opportunity to blame the fire on his political opponents, especially communists. In response, the government passed the Decree of the Reich President for the Protection of the People and State, which "abolished freedom of speech, assembly, privacy and the press; legalized phone tapping and interception of correspondence; and suspended the autonomy of federated states, like Bavaria". Communist politicians were arrested, leaving the Nazi Party free to do what they wanted. Hitler made Germany an absolute dictatorship, and he withdrew from the League of Nations. In 1934, during the Night of the Long Knives, Hitler ordered the purge of leaders within the Nazi Party's Sturmabteilung (SA) paramilitary organisation, believing them to have gotten too powerful. From 1919 to 1921, Italian fascist Benito Mussolini grew a base of supporters who wanted him to deal with Italy's political and economic crises, which involved civil conflict over the growth of socialism in the country. Many of Mussolini's supporters became known as blackshirts, who would form a paramilitary that terrorised the Italian countryside in a campaign against socialism. In 1922, during a controversial general strike by a weakened trade unionist movement, Mussolini and his followers seized power in Rome and installed him as the Prime Minister of Italy to run the country alongside the pre-existing monarchy of King Victor Emmanuel III. Similar to Germany, Mussolini turned the country into a one-party fascist state which outlawed free speech, the free press, trade unions, and targeted socialists, Catholics, and liberals with a network of secret police and spies. Italy became sympathetic to Nazi Germany in the 1930s.
Italy, Germany, and Imperial Japan — led by Emperor Hirohito and Prime Minister Hideki Tojo — increasingly allied with each other, and during World War II they would be known as the Axis powers. Italy and Japan needed allies, as Italy was involved in the Second Italo-Ethiopian War (the Italian invasion of the Ethiopian Empire) from 1935 to 1937, and Japan started the Second Sino-Japanese War (Japan's expanded invasion of the Republic of China) in 1937, the latter of which was subsumed by World War II and ended in 1945. In 1936, Italy and Germany made a pact of mutual assurance, the Rome-Berlin Axis agreement. Also that year, Japan and Germany signed the Anti-Comintern Pact to counter the perceived threat of communism from the Soviet Union led by Joseph Stalin; Italy joined the pact in 1937. Italy and Germany signed the Pact of Steel in 1939, formalising the Rome-Berlin axis. Other smaller powers joined the Axis throughout World War II. The Axis' main opponents would be the Allies, a name reused from the Allies who were the main opponent of the Central Powers in World War I.
=== Nazi social policies === Under the Nazi Party, Germany developed a hierarchy which considered the pseudoscientific "Aryan race" — white ethnic Germans or those closest genetically to them – as the most superior race, and Jews and Slavs at or near the bottom. A major part of Nazi Germany's racial policy was the concept of lebensraum, or "living space": increasing the amount of land in Europe where members of the Aryan race could live. The United States Holocaust Memorial Museum writes:
The Nazis also adopted the social Darwinist take on Darwinian evolutionary theory regarding the "survival of the fittest." For the Nazis, survival of a race depended upon its ability to reproduce and multiply, its accumulation of land to support and feed that expanding population, and its vigilance in maintaining the purity of its gene pool, thus preserving the unique "racial" characteristics with which "nature" had equipped it for success in the struggle to survive. Since each "race" sought to expand, and since the space on the earth was finite, the struggle for survival resulted "naturally" in violent conquest and military confrontation. Hence, war—even constant war—was a part of nature, a part of the human condition.This formed a key motivation of Germany's expansion in Europe in the mid-to-late 1930s. In 1934, Germany signed a non-aggression pact with Poland, but this would not last as Poland was considered a part of the lebensraum; Nazi mythology considered eastern Europe to be lost German land. In 1933, Germany began building concentration camps to hold their political enemies and those they considered "degenerates", such as people on the lower end of their racial hierarchy, the Nazi Party's political enemies (like socialists, social democrats, and communists), Poles, Romani people, Jehovah's Witnesses, Freemasons, disabled people, and LGBTQ people. They were brought from many places across lower continental Europe to the camps using the extensive railway network which crossed the continent. The mass killing of the camps' prisoners, which started as soon as they were built, expanded in 1941, which is usually when the start date of the Holocaust is given. In 1938, during the Kristallnacht pogroms, 30,000 Jews were sent to concentration camps. In 1938, German chemists Otto Hahn and Fritz Strassman discovered nuclear fission, or the release of large amounts of energy when an atom's nucleus splits into smaller nuclei. German scientists of the Uranverein (uranium club) then began a project to develop the atomic bomb, a bomb using nuclear fission that could destroy entire cities. This was supposed to be secret, but scientists fleeing Nazi Germany to avoid persecution made word of the program in other Western countries. In 1939, United States President Franklin D. Roosevelt was warned of the program by one of these fleeing scientists, Albert Einstein.
==== German expansion and the partition of Czechoslovakia ==== The UK and France responded to Germany's aggressive expansion through appeasement, "maintain[ing] peace in Europe by making limited concessions to German demands", which was seen as reasonable by the British and French populaces because the Treaty of Versailles was thought of as indeed too restrictive, and they did not want to go to war with Germany. In 1935, Germany revoked the Treaty of Versailles' limitations on its military, and remilitizared the Rhineland in 1936. On 13 March 1938, Germany annexed Austria in the Anschluss. Hitler then threatened to go to war with Czechoslovakia, and in response, on 30 September 1938, Hitler, Mussolini, UK prime minister Neville Chamberlain, and French premier Edouard Daladier signed the Munich Agreement, which gave Germany the Sudetenland, a Czech region near its border with Germany which had long been ethnically German. Chamberlain returned to England and proclaimed that the UK had achieved "Peace for our time". At the same time, Hungary annexed a part of southern Slovakia and Poland annexed the Tešin District of Czech Silesia. On 15 March 1939, Germany occupied the remaining western half of Czechoslovakia, the Czech provinces of Bohemia and Moravia. Later that month, part of Slovakia became the independent fascist and Catholic state of the Slovak Republic under dictator and Catholic priest Jozef Tiso. The republic was controlled by the Slovak People's Party, who made the country a client state of Germany and allowed Germany to occupy it. At the same time, the eastern part of Slovakia, the Subcarpathian Rus, was annexed by Hungary. The latter two annexations formally ended the country of Czechoslovakia, which had existed since 1918. By early 1939, Hitler had plans of invading Poland, despite Poland having assurances from the UK and France that those countries would intervene if Poland was attacked. Germany revoked its non-aggression pact with Poland on 28 April. To ensure Germany would not face resistance from the Soviet Union during an invasion, the two countries signed an agreement to neutrality named the Molotov–Ribbentrop Pact after secret negotiations from 23 to 24 August. Hitler gave the orders to invade on 26 August, certain that the UK and the Soviet Union would not retaliate. However, on the 25th, the UK and Poland publicly signed a formal treaty of military assurance, causing Hitler to delay the war for a few days. On 31 August, he gave the order to invade the next day.
Beginning of the war in Europe (1939–1940)
Invasion of Poland (1939)
On 1 September 1939, Germany invaded Poland, falsely claiming that Poland was trying to encircle and partition Germany and that ethnic Germans were being persecuted there. Germany had staged an attack on one of their own radio stations the previous night and blamed it on the Poles. 1.5 million soldiers of the German military, the Wehrmacht, took part in the invasion, and had overwhelming military superiority to Poland's 1 million soldiers. The invasion was led by generals Fedor von Bock, Franz Halder, Georg von Küchler, Gerd von Rundstedt, Günther von Kluge, Johannes Blaskowitz, Walther von Brauchitsch, Walther von Reichenau, and Wilhelm List. Poland fought on a large front, both on the German border and with their flanks in the German territory of East Prussia in the north and German-occupied Slovakia in the south. Poland did not move their troops eastward to more defensive positions because their western half had their most vital industrial regions. The Wehrmacht used "Blitzkrieg attacks", surprise attacks with "massive, concentrated forces of fast-moving [armoured] units supported by overwhelming air power". Their air force, the Luftwaffe, specifically operated as support for the Army. They quickly destroyed vital Polish infrastructure including the railways, essentially taking out the Polish Air Force before it could be used. In 1939, they surpassed the three current Allied powers in their individual numbers of infantry and armoured divisions (the Wehrmacht's armoured divisions are also known as panzer divisions). Germany also had more machine guns, mortars, antitank guns, and howitzers per division than the Allies, while having about an equal number of tanks and military aircraft to the three of them combined. New types of military technology invented in the interwar years included radar, the dive bomber, and the aircraft carrier. The Allied countries, motivated by their victory in World War I, had generally not worked to produce significant amounts of newer weapons and military equipment afterwards, feeling confident in what they already had, while Germany did the opposite since remilitarising in 1935. Poland did not have "tanks, armoured personnel carriers, and antitank and antiaircraft guns", and believed horsed cavalry could take on German mechanised forces. The UK and France did make up for Poland's lack of air strength; Poland only had fighters and bombers, and the other Allies had those plus aircraft meant for either reconnaissance, coastal defence, or naval aviation. The UK had ready the newer Hurricane fighter and was producing the Spitfire, which began combat in 1940. France's military aircraft, however, were outdated, and they were trying to buy newer models from the United States. The UK did not have any armoured divisions, and France's tanks were spread thin across its infantry divisions. The Allies in 1939 were "together superior in industrial resources, population, and military manpower", but German weapons, equipment, training and logistics made the Wehrmacht the most powerful army in the world. Britannica writes:
In accordance with the doctrines of General Heinz Guderian, the German tanks were used in massed formations in conjunction with motorized artillery to punch holes in the enemy line and to isolate segments of the enemy, which were then surrounded and captured by motorized German infantry divisions while the tanks ranged forward to repeat the process: deep drives into enemy territory by panzer divisions were thus followed by mechanized infantry and foot soldiers. These tactics were supported by dive bombers that attacked and disrupted the enemy's supply and communications lines and spread panic and confusion in its rear, thus further paralyzing its defensive capabilities. The only form of combat in which Germany had inferior capability was at sea, so they did not attack the Allies' navies with massed fleets, but instead through "the individual operation of German pocket battleships and commerce raiders". France and the UK declared war on Germany on 3 September, but they did not actually engage in warfare with Germany during the invasion of Poland. Meanwhile, the Battle of the Atlantic began over control of sea routes in the Atlantic Ocean. On 17 September, the Soviets invaded Poland, and the Poles now fought on two fronts. The next day, Polish government officials escaped into Romania, and for the next ten days, the Polish garrison in the capitol of Warsaw held on as Germans bombed the city massively, killing many civilians. On the 28th, Poland surrendered, and the next day, Germany and Soviet Union partitioned the county between them in accordance with a secret provision of the Molotov-Ribbentrop Pact. The provision originally stated the western third of Poland would be given to the Germans, and the eastern two-thirds to the Soviets, while Lithuania would be put in the German sphere of influence; now, the two countries agreed to let Lithuania fall under the Soviet sphere of influence if more of Poland was given to Germany. The last Polish unit surrendered on 6 October. The invasion ended with 14,000 Germans dead or missing and 66,000 to 70,000 Poles dead. 700,000 Poles were taken prisoner and 80,000 escaped into neutral countries. From October 1939 to March 1940, the European theatre was in a phase known as the Phoney War, when no major land operations were made by the Allied powers.
=== Winter War and Soviet occupation of the Baltics (1939–1940) === As early as August 1935, the Soviets' Leningrad commissar Andrei Zhdanov had started making observations of their border with Finland. Based on these observations, the Soviets began building railway spur tracks leading west toward Finnish wilderness, in particular toward Kuusamo, Suomussalmi, Kuhmo, and Lieksa. The tracks were meant for a future invasion of Finland; they could have served no other purpose than to transport troops and material, since little trade passed through these regions.
Finland and the Baltic states – Lithuania, Latvia, and Estonia — were allocated to the Soviet sphere of influence in the Molotov-Ribbentrop Pact. On 10 October 1939, the Soviets demanded the Baltic states to allow Soviet garrisons to be stationed within them. The countries felt threatened, resentfully agreeing to sign pacts of mutual assurance allowing the soldiers in. The beginning of World War II escalated tensions between Finland and the Soviet Union. The Soviets thought the Axis would use Finland as a base to attack them, and the Finns thought the Soviets were trying to expand into Finnish territory. The Soviets then forwarded demands to Finland that were similar to the demands sent to the Baltic states; the Finns also had to destroy their defensive Mannerheim Line along the Karelian Isthmus near the border with the Soviet Union. Finland rejected these demands, instead mobilising their army and unsuccessfully attempting to gain Allied support. On 30 November 1939, the Soviet Union invaded Finland, justifying it with a staged incident at the countries' border. Thus began the Winter War, with the Soviet objective being the conquest of Finland and the installation of a communist puppet government in Helsinki. At the start of the war, the Soviets suffered severe losses and made little progress. The Finns made use of the Molotov cocktail, a type of makeshift grenade, naming it after Soviet Foreign Minister Vyacheslav Molotov who was blamed for the war. The Finns, who had little outside help, became worn down in a war of attrition. The Soviets reduced their strategic objectives in late January 1940 and put an end to the puppet Finnish communist government, and informed the legitimate Finnish government that they were willing to negotiate peace. After the Soviets reorganised and adopted different tactics, they renewed their offensive in February and breached the Mannerheim Line. On 6 March, Finland asked for peace terms, and on the 12th, the two countries signed the Moscow Peace Treaty, in which the Finns ceded 9% of their territory to the Soviet Union, and the Hanko Peninsula was leased to the Soviets for 30 years. The war ended the following day. In June 1940, Joseph Stalin sent another set of ultimatums to the Baltic states, demanding the allowance of an unlimited number of Soviet troops into their countries and to form governments under Soviet terms. All three countries were occupied by within a few months and the Soviet Union quickly began the process of Sovietization, the enforcing of communist-led people's assemblies ("soviets") which would be the new governmental bodies. The new Baltic soviets voted for their countries to become republics of the Soviet Union; the Soviet Union formally accepted these additions in August 1940.
=== Scandinavian fronts (April–June 1940) === On 9 April 1940, in Operation Weserübung, Germany invaded Denmark and Norway as essentially a preventative measure to stop the UK and France from occupying Norway, as well as to protect German industry; Britain previously had set up naval blockades between Norway and Germany which cut off the import of iron from northern Sweden that was being shipped out of the Norwegian port of Narvik. The invasion was led by General of the Infantry Nikolaus von Falkenhorst. Germany notified the UK and France of the invasion in a memorandum claiming that the Allies were trying to use Scandinavia as a base from which to attack Germany from the north, and that Scandinavia needed to be protected from Allied "aggression". In the opening battle of the invasion, the Battle of Drøbak Sound, the Norwegians won and the German advance was slowed down.
Norwegian resistance quickly faltered, however, and Norwegian government heads fled for the countryside. Vidkun Quisling, of the Nasjonal Samling fascist party, proclaimed a new government on the evening of 9 April 1940, and he became the Prime Minister of Norway under Germany's administration during the war. Norway's army agreed to cooperate with Germany, and began attacking the Allies. The UK tried to defend Norway with ground, air, and sea presence, but it was difficult. On 27 April, the British ground soldiers began to retreat. On 28 May, the British recaptured Narvik, but the Axis took it again on 9 June. The invasion was over by 10 June 1940. The British occupied the Faroe Islands in response to Germany's gains. Sweden was able to remain neutral.
=== Positions of Spain and Portugal === In 1936, insurgents led by fascist Francisco Franco went to war with the democratically elected Spanish government in the Spanish Civil War. Hitler sided with Franco, giving aid to the insurgents. In 1939, Franco won the war, becoming the dictator of Spain. Before that, though, in early 1939, many Spaniards crossed the border into France, where they were given a choice by the French government whether to return to Spain (and be punished by Franco), or join the French military; during World War II, many Spanish soldiers fought for the Third French Republic (the French government before Germany invaded) and later for the French resistance against the Nazis. Spain claimed neutrality during World War II, but collaborated with the Axis. They gave Germany raw materials to use in weapons production. 10,000 to 15,000 Spaniards that were previously refugees in France were deported to Germany, where about 60% were killed by the Nazis. Portugal claimed neutrality as well, but they allowed the British to access Portuguese bases in the Azores.
Axis expansion (1940–1941)
German invasion of Western Europe (1940)
On 10 May 1940, Germany began an invasion of France and the Low Countries (the Netherlands, Belgium, and Luxembourg). Three German commanders, Willhelm von Leeb, Fedor von Bock, and Gerd von Rundstedt took control of an army each and invaded France through the northern end of its German border, and also by crossing into France through the Low Countries, the latter movement resembling the Schlieffen Plan from World War I. On the 10th, the Germans first entered the Netherlands and Belgium, and Neville Chamberlain resigned, making Winston Churchill the prime minister of the United Kingdom. Chamberlain had been criticised for the failure of the Norwegian campaign, and Churchill had become the Labour Party's choice for leading the nation – even if they disliked his anti-socialist beliefs – because of his willingness to fight Germany. A coalition government was formed, led by a war cabinet of Churchill, Chamberlain, the conservative Lord Halifax, and the Labour members Clement Attlee and Arthur Greenwood. Churchill also became the Minister of Defence. On 12 May, the Dutch Queen Wilhelmina fled with her ministers to England, where she established the Dutch government-in-exile. The next day, the Germans crossed the Meuse river, entering France.
=== British invasion of Iceland (1940) === Winston Churchill, meanwhile, tried to convince Iceland to join the Allies, but they wanted to stay neutral. Ultimately, the UK decided to invade, as the country was strategically important as a base to control the North Atlantic. The invasion began on 10 May 1940. The government disliked the violation of their sovereignty, but capitulated to the UK, who occupied the country. The UK promised to compensate the Icelandic population and leave at the end of the war. Canadian troops arrived in Iceland in June 1940 and the Americans arrived a year later; foreign troops continued staying in Iceland after the war, as the country became a NATO member.
=== Fall of France (1940) === On 14 May 1940, Dutch Commander-in-Chief Henri Winkelman surrendered his forces east of the Scheldt river, essentially all of the Netherlands. On the 15th, French general Maurice Gamelin reported to French premier Paul Reynard that the Germans might take Paris within days. Reynard then replaced Gamelin with retired general Maxime Weygand, who was in Syria. Weygand arrived from Syria on the 19th, leaving the French high command without a top general for days while the Germans pushed towards Paris. Weygand arrived and replaced 12 generals, notably employing general Charles de Gaulle. The Germans broke through the French line on the 15th and marched swiftly into undefended land. They reached the English Channel by the 20th, and days later, moved north towards Calais and Dunkirk. The Belgians became encircled in Flanders. On the 24th, the Germans almost reached Dunkirk, but Hitler ordered them back, giving the British Expeditionary Forces and other Allies in Dunkirk some time to evacuate to England. They moved quickly, and the situation worsened on the 27th, when Leopold III, the king of Belgium, surrendered his army. The Allies successfully evacuated by 4 June, saving 198,000 British men and 140,000 French men. At this point, the French front had been pushed back to the Somme and Aisne rivers. French numbers and morale weakened, and many retreated westward across France. On 9 June, the Germans crossed the Seine. On 10 June 1940, Italy declared war on France and the United Kingdom. They began attacking France on the 20th, but it made little effect. Reynaud had fled Paris to Tours, and he and his ministers were told by Weygand on the 12th that the French battle had been lost. Meanwhile, French Major General Victor Fortune surrendered his 10,000 men of the British Expeditionary Forces' 51st Highland Division who were being exhausted at Saint-Valéry-en-Caux. On the 14th, the French military evacuated Paris and the Germans entered the city. Reynaud again moved the government, this time to Bordeaux. The next day, Verdun fell, and on the 16th, Reynaud resigned, being succeeded by Philippe Petain. On the 17th, Petain asked the Germans for an armistice. On 18 June 1940, de Gaulle asked the French people, in a speech from London, to resistance against the Germans. The terms were dictated with Hitler on the 21st, and on the 25th, war between France and Germany/Italy was officially over. On 22 June, France was divided into two sections under the Franco-German Armistice; one was occupied by the German military and the other, Vichy France, had some autonomy. The Chasselay massacre occurred in France in June 1940.
Battle of Britain and the Blitz (1940)
Starting in June 1940, in the Battle of Britain, the German Luftwaffe air branch launched air assaults on the United Kingdom in preparation to launch an amphibious invasion of Britain codenamed Operation Sea Lion. The British Royal Air Force (RAF) successfully defended Britain, and that phase of bombing ended in September 1940. On 7 September, the Luftwaffe started an aerial bombing campaign on Britain known as the Blitz, which instead destroyed strategic targets to hurt the British war effort.
During the Battle of Britain, the UK asked the U.S. for help, but the American public was divided over the need to get involved in the war. In the November 1940 U.S. presidential election, the incumbent President Franklin D. Roosevelt was elected to his third term in office. America was becoming more certain of the need to send aid to the UK; for example, Roosevelt's main opponent in the election, Wendell Willkie of the Republican Party, differed from his party's previous sentiment by agreeing to give aid. In December 1940, president-elect Roosevelt gave a speech in which he explained his "Arsenal of democracy" approach to the war and justifying providing the UK with aid. In March 1941, the U.S. Congress passed the Lend-Lease Act, which allowed the U.S. to send large amounts of aid: it ranged from "tanks, aircraft, ships, weapons and road building supplies to clothing, chemicals and food." The program soon expanding to giving aid to the Soviet Union, China, and allied France.
=== Italian invasion of Greece (1940–1941) === On 28 October 1940, Italy began invading Greece. This surprised the Greeks, as well as Hitler, who did not want Axis troops to be taken away from the North African campaign. Mussolini was convinced that Italy would quickly win, but they were pushed back into Albania after a week. The Italians then spent the next three months in Albania defending against the Greeks. At the Battle of Taranto, the British navy destroyed almost half of the Italian fleet. In March 1941, the British sent 58,000 Commonwealth troops to help Greece, despite their intense combat in North Africa.
The Holocaust begins (1940–1941)
From 20 to 24 November 1940, Hungary, Romania, and Slovakia joined the Axis powers under the Tripartite Pact. In 1941, Hitler and other Nazi Party leaders including Heinrich Himmler and Reinhard Heydrich agree on a program of mass extermination of Jews throughout occupied Europe, beginning the Holocaust; this was referred to as the "Final Solution" to the "Jewish question", or the debate over what should happen to the Jews living on the continent. On 1 March 1941, Himmler ordered the construction of the Auschwitz-Birkenau concentration camp. At the same time, Bulgaria joined the Tripartite Pact, and two days later, Germany began sealing off a Jewish ghetto in Krakow, Poland. Aside from concentration camps, the Final Solution was also enacted with Einsatzgruppen, mobile killing units. Croatia joined the Tripartite Pact on 15 June.
=== German invasion of Yugoslavia and Greece (1941) === On 6 April 1941, Germany, aided by Bulgarian and Hungarian forces, started invading Yugoslavia and Greece. This was to help the Italian invasion of Greece, overthrow the pro-Allied Yugoslavia government, secure the German flank during the planned invasion of Russia, protect German oil in Romania from Allied air attacks, and create a base to attack British communication lines with the east. Major Yugoslavian cities, including Belgrade, were bombed. On 17 April, Yugoslavia capitulated, as Germany moved into northern Greece. Greek cities were subject to Blitzkrieg attacks; despite intense resistance, Athens fell on 27 April. 2,500 Germans were killed. 11,000 Allied men were captured, and 45,000 evacuated to the island of Crete. On 20 May 1941, Germany began an invasion of Crete. They launched paratrooper assaults on multiple Cretan cities, overwhelming the Allies, who evacuated the island. Germany fought off guerrilla resistance in Yugoslavia and Greece for the rest of the war. In late 1941, the Brits started aiding the Chetnik guerrillas, led by Dragoljub Mihailovic. Eventually, the Chetniks fought in a civil war against another group of guerrillas, the Partisans, led by Josip "Tito" Broz. The Chetniks collaborated with the Allies, and in 1943, the British switched their alliance to the Partisans. In Greece, the communist ELAS fought a civil war with the republican EDES. They fought until a peace deal was made by the Allies.
Greatest extent of Axis power (1941–1943)
Eastern Front (June–July 1941)
On 22 June 1941, Germany launched the invasion of the Soviet Union, code-named Operation Barbarossa. It had originally been planned for May, but Hitler used his troops to invade Yugoslavia and Greece, which was a more pressing matter. The campaigns in southern Europe were quick, but June would end up being a less ideal date for Barbarossa, as it was closer to the brutal Russian winter. Hitler and the Nazi High Command were convinced that by October, Germany would have taken the entirety of European Russia and the Soviet regime would collapse after losing support domestically. 3 million German soldiers were involved in Barbarossa, the largest invasion force in history. The northern end of the invasion was led by Wilhelm von Leeb; the center by Fedor von Bock, Heinz Guderian, and Hermann Hoth; and the south by Gerd von Rundstedt and Paul Ludwig von Kleist. The Soviets were taken by surprise, and had trouble creating an opposing force in time. By 27 June 1941, the Germans had reached Minsk. The local Soviets were encircled; 300,000 became prisoners, while others escaped to the east. Guderian crossed the Dnieper river on 10 July, and on the 16th, his troops entered Smolensk, taking 200,000 prisoners. Meanwhile, the Soviets used a scorched earth policy, burning many parts of western Russia. The western manufacturing industries were moved eastward. At the same time, series of storms had turned the roads to Russia into mud, and the German tanks moved slowly. However, by mid-July, the Germans had moved 640 kilometres east from their starting positions, and were 320 kilometres to Moscow. At the end of July, the Germans broke through the Soviet front in Kiev. 520,000 Soviets were encircled and captured.
=== Eastern Front (September–December 1941) === Operation Reinhard, named after Reinhard Heydrich, began in the autumn of 1941. It was the plan to kill the two million Jews living in occupied Poland. For this purpose, Germany constructed three extermination camps, Bełżec, Sobibór, and Treblinka, and the Reich Security Main Office led by Heydrich deported Polish Jews to these locations. By the end of the war, around 1.5 million Jews were killed in the three camps. German police and the Schutzstaffel (SS) also led a number of killing missions. Operation Reinhard was directed by SS general Odilo Globocnik from autumn 1941 until summer 1943. It had overlap with Aktion T4, or Germany's program of euthanising disabled people with carbon monoxide gas. As the Soviet Union was in a weakened position, in 1941, Finland used the opportunity to start the Continuation War, an attempt to take back the lands that they had lost during the Winter War. It would be fought until 1944. On 8 September 1941, Germany and Finland began the Siege of Leningrad, which also continued until 1944. In October 1941, at Vyazma, 600,000 of them were encircled and captured. On 19 September 1941, the Germans entered the city of Kiev in Ukraine. Some of them were killed in explosions from mines left by retreating Soviet soldiers, and the Germans used this as a pretext to take revenge on the local Jews, whom the explosions were blamed on. From the 29th to the 30th, in the Babi Yar massacre, approximately 33,771 of Kiev's Jews were massacred. They had been summoned to a ravine near the city, where they were made to undress and enter the ravine before being shot. In October 1941, the Siege of Sevastopol started when Germany and Romania tried to take Sevastopol from the Soviets. Soviet resistance prolonged the siege, but the Axis took the city in July 1942. In the First Battle of Kharkov from 20 to 24 October, the German Sixth Army successfully took the city of Kharkov where the Soviets had been producing their T-34 tanks. After the city's capture, the Germans discovered the tanks' production had been moved out of the city prior to the battle.
As winter approached, the Germans in the Soviet Union were beaten down by cold weather; many got frostbite and had their military equipment freeze. Meanwhile, new waves of Soviets came to defend the front. On 22 November 1941, the Germans reached Rostov-na-Donu, an important location to continue the Caucasus campaign, but the Soviets launched a counteroffensive and took back the city on the 28th. On 2 December, some Germans had reached the suburbs of Moscow, but this is the closest they got to the center of the city. On 6 December, Soviet commander Georgy Zhukov started a large counteroffensive at Moscow which confirmed Barbarossa's failure.
=== America joins the war (1941) === Imperial Japan declared war on the United States by attacking the American military base at Pearl Harbor in Hawaii on 7 December. The next day, the Japanese ambassador Hiroshi Oshima went to German Foreign Minister Joachim von Ribbentrop, asking him to finally have Germany declare war on the United States. von Ribbentrop believed that the Americans entering the war would overwhelm the German war effort, but Hitler did not think so. On 11 December, Germany declared war on the United States, and the next day, Hitler defended the decision in a speech to the Reichstag. He claimed that Roosevelt's New Deal policies were the actual cause of World War II.
=== Operation Archery (1941) === On 27 December 1941, the British Army, Royal Navy, and the RAF launched Operation Archery, an attack on the Axis in the town of Måløy on Vaagso Island, Norway. The objective was to "sink, burn and destroy any enemy shipping found in the convoy assembly anchorage, and to put out of action the garrison (kill or capture) and the German installations in the port including the fish factories." Two British Commando units attacked, one to attack the German garrison in the town and the other to stop the German guns at the nearby Maaloy Island. The Army was supported by the British cruiser HMS Kenya and RAF aircraft taking off from Scotland and the Shetlands. The British sunk eight German ships and 120 Germans were killed before the British quickly retreated. The tactics of the operation would be used the Allies during the later Normandy landings.
Western Front (February–May 1942)
On 12 February 1942, in Operation Cerberus or the Channel Dash, three of the Kriegsmarine's biggest ships (Gneisenau, Prinz Eugen, and Scharnhorst) attempted to move from Brest, France — a vital German naval port — to the German coast in the North Sea through the English Channel's slim Dover Strait, despite the presence of the Royal Navy and RAF Coastal Command there. Once at Germany, they were supposed to be used for defending Norway. As part of the pre-existing Operation Fuller, launched in 1941 to defend the channel, the British responded with naval and air power; the Luftwaffe defended the Germans. The British destroyed some German aircraft, but the Royal Navy and RAF faced heavy losses and were unable to prevent the ships from reaching their destination. The ships' later use was limited, however. On 28 March 1942, in Operation Chariot or the St Nazaire Raid, the Royal Navy attacked the German dry dock at St Nazaire in occupied France. The dock served as one of the bases of operation for German U-boats, and was defended by 6,000 soldiers. If it was destroyed, then the powerful German battleship Tirpitz — which had been defending Norway – could not be repaired at St Nazaire during potential future involvement in the Battle of the Atlantic, instead having to take trips to two other docks, during which the British could attack her easier. Operation Chariot used 611 British soldiers, first destroying the gate to the dock with the destroyer HMS Campbeltown, then attacking the ships. The British faced heavy losses, with 169 of them killed and 200 taken prisoner, but they greatly hurt the German navy, forcing Germany to divert troops from elsewhere to defend their Atlantic operations. On the night of 30–31 May 1942, the RAF Bomber Command performed Operation Millennium. 1,047 bombers - the command's first raid involving more than 1,000 bombers – led by the Commander-in-Chief of the Bomber Command, Arthur Harris, launched a raid on Cologne, Germany. This used 2+1⁄2 times more pilots than any previous night raid, and was important for publicity and psychological warfare. Harris gathered large amounts of spare aircraft, and had some of them used by those who were still in pilot training. The raid was a success, starting more than 2,500 fires, destroying around 13,000 buildings, and killing less than 500 people. 41 RAF aircraft were lost. The operation's tactics were implemented by the Bomber Command for future use during the war. 135,000 to 150,000 of the city's previous population of around 700,000 fled.
=== German and American atomic bomb programs (1942–1945) === In summer 1942, the U.S. began the Manhattan Project, or their top-secret atomic bomb program in response to Germany's own program. The Manhattan Project was led by physicist J. Robert Oppenheimer, and was worked on mainly in Hanford, Washington; Los Alamos, New Mexico; and Oak Ridge, Tennessee. The U.S. overestimated Germany's program, which was cancelled as a military project in July 1942 and continued as a civilian project; it became disorganised as its Jewish scientists continued to escape Nazism, and was underfunded as Hitler did not understand its purpose. In 1944, as Berlin was increasingly bombed, Germany's program moved from Berlin to Haigerloch. There, scientists unsuccessfully attempted to build a nuclear reactor instead of a nuclear bomb; as Germany weakened, the program shut down.
=== Eastern Front (April 1942 – March 1943) === In 1942, Reinard Heydrich was assassinated by Czech agents while in Prague. On 27 May, he was travelling through the city in an open vehicle; he did not give himself appropriate security, as he was convinced of the efficacy of his anti-resistance campaign within German-occupied Europe. His car went through a usual route taken to get to the nearby airport, where he would fly back to Hitler's headquarters. Along the way, Free Czech parachute agents (who had been trained in Britain) rolled a hand grenade under the vehicle. Heydrich was not immediately killed, but his leg and back were hit with grenade splinters, causing an infection which killed him on 4 June 1942. On 9 June, the day of his funeral in Berlin, Hitler announced attacks targeting Czechs in retaliation, and the towns of Lidice and Ležáky were destroyed. In the Second Battle of Kharkov from 12 to 28 May 1942, Soviet marshal Semyon Timoshenko attempted to recapture Kharkov from the Germans. 170,000 Soviets were killed and 106,000 wounded as they faced major resistance from Fedor von Bock, but the Soviets retook the city after it had been mostly destroyed.
