Invasion of Poland in the context of "Franz Halder"

World War II or the Second World War (1 September 1939 – 2 September 1945) was a global conflict between two coalitions: the Allies and the Axis powers. Nearly all of the world's countries participated, with many nations mobilising all resources in pursuit of total war. Tanks and aircraft played major roles, enabling the strategic bombing of cities and delivery of the first and only nuclear weapons ever used in war. World War II is the deadliest conflict in history, causing the death of 70 to 85 million people, more than half of whom were civilians. Millions died in genocides, including the Holocaust, and by massacres, starvation, and disease. After the Allied victory, Germany, Austria, Japan, and Korea were occupied, and German and Japanese leaders were put on trial for war crimes.

The causes of World War II included unresolved tensions in the aftermath of World War I, the rise of fascism in Europe and militarism in Japan. Key events preceding the war included Japan's invasion of Manchuria in 1931, the Spanish Civil War, the outbreak of the Second Sino-Japanese War in 1937, and Germany's annexations of Austria and the Sudetenland. World War II is generally considered to have begun on 1 September 1939, when Nazi Germany, under Adolf Hitler, invaded Poland, after which the United Kingdom and France declared war on Germany. Poland was divided between Germany and the Soviet Union under the Molotov–Ribbentrop Pact. In 1940, the Soviet Union annexed the Baltic states and parts of Finland and Romania. After the fall of France in June 1940, the war continued mainly between Germany, now assisted by Fascist Italy, and the British Empire, with fighting in the Balkans, Mediterranean, and Middle East, the aerial Battle of Britain and the Blitz, and the naval Battle of the Atlantic. Through campaigns and treaties, Germany gained control of much of continental Europe and formed the Axis alliance with Italy, Japan, and other countries. In June 1941, Germany invaded the Soviet Union, opening the Eastern Front and initially making large territorial gains.

Nazi Germany, officially the German Reich and later the Greater German Reich, was the German state between 1933 and 1945, when Adolf Hitler and the Nazi Party controlled the country, transforming it into a totalitarian dictatorship. The Third Reich, meaning "Third Realm" or "Third Empire", referred to the Nazi claim that Nazi Germany was the successor to the earlier Holy Roman Empire (800–1806) and German Empire (1871–1918). The Third Reich, which the Nazis referred to as the Thousand-Year Reich, ended in May 1945, after 12 years, when the Allies defeated Germany and entered the capital, Berlin, ending World War II in Europe.

After Hitler was appointed Chancellor of Germany in 1933, the Nazi Party began to eliminate political opposition and consolidate power. A 1934 German referendum confirmed Hitler as sole Führer (leader). Power was centralised in Hitler's person, and his word became the highest law. The government was not a co-ordinated, cooperating body, but rather a collection of factions struggling to amass power. To address the Great Depression, the Nazis used heavy military spending, extensive public works projects, including the Autobahnen (motorways) and a massive secret rearmament program, forming the Wehrmacht (armed forces), all financed by deficit spending. The return to economic stability and end of mass unemployment boosted the regime's popularity. Hitler made increasingly aggressive territorial demands, seizing Austria in the Anschluss of 1938, and the Sudetenland region of Czechoslovakia. Germany signed a non-aggression pact with the Soviet Union and invaded Poland in 1939, launching World War II in Europe. In alliance with Fascist Italy and other Axis powers, Germany conquered most of Europe by 1940 and threatened Britain.

The Holocaust (/ˈhɒləkɔːst/ HOL-ə-kawst), known in Hebrew as the Shoah (/ˈʃoʊə/ SHOH-ə; Hebrew: שּׁוֹאָה, romanized: Shoah, IPA: [ʃoˈʔa], lit. 'Catastrophe'), was the genocide of European Jews during World War II. From 1941 to 1945, Nazi Germany and its collaborators systematically murdered some six million Jews across German-occupied Europe, around two-thirds of Europe's Jewish population. The murders were committed primarily through mass shootings across Eastern Europe and poison gas chambers in extermination camps, chiefly Auschwitz-Birkenau, Treblinka, Belzec, Sobibor, and Chełmno in occupied Poland. Separate Nazi persecutions killed millions of other non-Jewish civilians and prisoners of war (POWs); the term Holocaust is sometimes used to include the murder and persecution of non-Jewish groups.

The Nazis developed their ideology based on racism and pursuit of "living space", and seized power in early 1933. Meant to force all German Jews to emigrate, regardless of means, the regime passed anti-Jewish laws, encouraged harassment, and orchestrated a nationwide pogrom known as Kristallnacht in November 1938. After Germany's invasion of Poland in September 1939, occupation authorities began to establish ghettos to segregate Jews. Following the June 1941 invasion of the Soviet Union, 1.5 to 2 million Jews were shot by German forces and local collaborators. By early 1942, the Nazis decided to murder all Jews in Europe. Victims were deported to extermination camps where those who had survived the trip were killed with poisonous gas, while others were sent to forced labor camps where many died from starvation, abuse, exhaustion, or being used as test subjects in experiments. Property belonging to murdered Jews was redistributed to the German occupiers and other non-Jews. Although the majority of Holocaust victims died in 1942, the killing continued until the end of the war in 1945.

The causes of World War II have been given considerable attention by historians. The immediate precipitating event was the invasion of Poland by Nazi Germany on September 1, 1939, and the subsequent declarations of war on Germany made by Britain and France, but many other prior events have been suggested as ultimate causes. Primary themes in historical analysis of the war's origins include the political takeover of Germany in 1933 by Adolf Hitler and the Nazi Party; Japanese militarism against China, which led to the Japanese invasion of Manchuria and the Second Sino-Japanese War; Italian aggression against Ethiopia, which led to the Second Italo-Ethiopian War; or military uprising in Spain, which led to the Spanish Civil War.

During the interwar period, deep anger arose in the Weimar Republic over the conditions of the 1919 Treaty of Versailles, which punished Germany for its role in World War I with heavy financial reparations and severe limitations on its military that were intended to prevent it from becoming a military power again. The demilitarisation of the Rhineland, the prohibition of German unification with Austria, and the loss of its overseas colonies as well as some 12% of the pre-war land area and population of the metropole all provoked strong currents of revanchism in German politics.

Adolf Hitler (20 April 1889 – 30 April 1945) was an Austrian-born German politician who was the dictator of Germany during the Nazi era, which lasted from 1933 until his suicide in 1945. He rose to power as the leader of the Nazi Party, becoming the chancellor of Germany in 1933 and then taking the title of Führer und Reichskanzler in 1934. Germany's invasion of Poland on 1 September 1939 under his leadership marked the outbreak of the Second World War. Throughout the ensuing conflict, Hitler was closely involved in the direction of German military operations as well as the perpetration of the Holocaust, the genocide of about six million Jews and millions of other victims.

Hitler was born in Braunau am Inn in Austria-Hungary and moved to Germany in 1913. He was decorated during his service in the German Army in the First World War, receiving the Iron Cross. In 1919, he joined the German Workers' Party (DAP), the precursor of the Nazi Party, and in 1921, was appointed the leader of the Nazi Party. In 1923, he attempted to seize governmental power in a failed coup in Munich and was sentenced to five years in prison, serving just over a year. While there, he dictated the first volume of his autobiography and political manifesto Mein Kampf (lit. 'My Struggle'). After his early release in 1924, he gained popular support by attacking the Treaty of Versailles as well as promoting pan-Germanism, antisemitism, and anti-communism with charismatic oratory and Nazi propaganda. He frequently denounced communism as being part of an international Jewish conspiracy. By November 1932, the Nazi Party held the most seats in the Reichstag, but not a majority. Former chancellor Franz von Papen and other conservative politicians convinced President Paul von Hindenburg to appoint Hitler as chancellor on 30 January 1933. Shortly thereafter on 23 March, the Reichstag passed the Enabling Act of 1933, which ultimately began the Weimar Republic's transformation into Nazi Germany.

On 3 September 1939, King George VI declared war on Germany—two days after the German invasion of Poland. France also declared war on Germany later the same day.

On 3 September 1939—two days after the German invasion of Poland—France declared war on Nazi Germany according to its defensive treaty with Poland, when France's ultimatum to Germany, issued the previous day, expired at 17:00. This occurred hours after the United Kingdom declaration of war on Germany.

The Battle of France (French: bataille de France; 10 May – 25 June 1940), also known as the Western Campaign (German: Westfeldzug), the French Campaign (Frankreichfeldzug, campagne de France) and the Fall of France, during the Second World War was the German invasion of the Low Countries (Belgium, Luxembourg and the Netherlands) and France. The plan for the invasion of the Low Countries and France was called Fall Gelb (Case Yellow or the Manstein plan). Fall Rot (Case Red) was planned to finish off the French and British after the evacuation at Dunkirk. The Low Countries and France were defeated and occupied by Axis troops down to the Demarcation line.

On 3 September 1939, France and Britain declared war on Nazi Germany, over the German invasion of Poland on 1 September. In early September 1939, the French army began the limited Saar Offensive but by mid-October had withdrawn to the start line. On 10 May 1940, Wehrmacht armies invaded Belgium, Luxembourg, the Netherlands and parts of France.

Warsaw, officially the Capital City of Warsaw, is the capital and largest city of Poland. The metropolis stands on the River Vistula in east-central Poland. Its population is officially estimated at 1.86 million residents within a greater metropolitan area of 3.27 million residents, which makes Warsaw the 6th most-populous city in the European Union. The city area measures 517 km (200 sq mi) and comprises 18 districts, while the metropolitan area covers 6,100 km (2,355 sq mi). Warsaw is classified as an alpha global city, a major political, economic and cultural hub, and the country's seat of government. It is also the capital of the Masovian Voivodeship.

Warsaw traces its origins to a small fishing town in Masovia. The city rose to prominence in the late 16th century, when Sigismund III decided to move the Polish capital and his royal court from Kraków. Warsaw surpassed Gdańsk as Poland's most populous city by the 18th century. It served as the capital of the Polish–Lithuanian Commonwealth until 1795, and subsequently as the seat of Napoleon's Duchy of Warsaw. The 19th century and its Industrial Revolution brought a demographic boom, which made it one of the largest and most densely populated cities in Europe. Known then for its elegant architecture and boulevards, Warsaw was bombed and besieged at the start of World War II in 1939. Much of the historic city was destroyed and its diverse population decimated by the Ghetto Uprising in 1943, the general Warsaw Uprising in 1944, and systematic razing.