Nazi Germany in the context of "Fascism"

A declaration of war is a formal act by which one state announces existing or impending war activity against another. The declaration is a performative speech act (or the public signing of a document) by an authorized party of a national government, in order to create a state of war between two or more states.

The legality of who is competent to declare war varies between nations and forms of government. In many nations, that power is given to the head of state or sovereign. In other cases, something short of a full declaration of war, such as a letter of marque or a covert operation, may authorise war-like acts by privateers or mercenaries. The official international protocol for declaring war was defined in the Hague Convention (III) of 1907 on the Opening of Hostilities.

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.

Norway, officially the Kingdom of Norway, is a Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of Norway. Bouvet Island, located in the Subantarctic, is a dependency, and not a part of the Kingdom; Norway also claims the Antarctic territories of Peter I Island and Queen Maud Land. Norway has a population of 5.6 million. Its capital and largest city is Oslo. The country has a total area of 385,207 square kilometres (148,729 sq mi). The country shares a long eastern border with Sweden, and is bordered by Finland and Russia to the northeast. Norway has an extensive coastline facing the Skagerrak strait, the North Atlantic Ocean, and the Barents Sea. In 2024, Norway was ranked the seventh happiest country in the world.

The unified kingdom of Norway was established in 872 as a merger of petty kingdoms and has existed continuously for 1,152–1,153 years. From 1537 to 1814, Norway was part of Denmark–Norway, and, from 1814 to 1905, it was in a personal union with Sweden. Norway was neutral during the First World War, and in the Second World War until April 1940 when it was invaded and occupied by Nazi Germany until the end of the war.

During World War II, the Crimean Peninsula was subject to military administration by Nazi Germany following the success of the Crimean campaign. Officially part of Generalbezirk Krym-Taurien, an administrative division of Reichskommissariat Ukraine, Crimea proper never actually became part of the Generalbezirk, and was instead subordinate to a military administration. This administration was first headed by Erich von Manstein in his capacity as commander of the 11th Army and then by Paul Ludwig Ewald von Kleist as commander of Army Group A.

German interests in Crimea were multifaceted and a matter of great sensitivity due to German–Turkish relations, with Turkey serving as the primary champion of the rights of Crimean Tatars. Basing their interests in Crimea off of the historical existence of the Crimean Goths (the last surviving Gothic peoples), German authorities sought to transform Crimea into a tourist destination, including the deportation and genocide of Crimea's non-German inhabitants. Plagued by Soviet resistance from the outset of occupation, they failed to establish order to any extent that allowed for colonisation to take place, and lost further support due to the slow pace of land reform programmes and a lack of response to Crimean Tatar nationalist sentiment.

The deportation of the Crimean Tatars (Crimean Tatar: Qırımtatar halqınıñ sürgünligi, Cyrillic: Къырымтатар халкъынынъ сюргюнлиги) or the Sürgünlik ('exile') was the ethnic cleansing and the cultural genocide of at least 191,044 Crimean Tatars that was carried out by Soviet Union authorities from 18 to 20 May 1944, supervised by Lavrentiy Beria, chief of Soviet state security and the secret police, and ordered by the Soviet leader Joseph Stalin. Within those three days, the NKVD used cattle trains to deport the Crimean Tatars, even Soviet Communist Party members and Red Army soldiers, from Crimea to the Uzbek SSR, several thousand kilometres away. They were one of several ethnicities that were subjected to Stalin's policy of population transfer in the Soviet Union.

Officially, the Soviet government presented the deportation as a policy of collective punishment, based on its claim that some Crimean Tatars collaborated with Nazi Germany in World War II, despite the fact that the 20,000 who collaborated with the Axis powers were half the 40,000 who served in the Soviet Red Army. Several modern scholars believe rather that the government deported them as a part of its plan to gain access to the Dardanelles and acquire territory in Turkey, where the Turkic ethnic kin of the Tatars lived, or remove minorities from the Soviet Union's border regions. By the end of the deportation, not a single Crimean Tatar lived in Crimea, and 80,000 houses and 360,000 acres of land were left abandoned. Nearly 8,000 Crimean Tatars died during the deportation, and tens of thousands subsequently perished due to the harsh living conditions in which they were forced to live during their exile. After the deportation, the Soviet government launched an intense detatarization campaign in an attempt to erase the remaining traces of Crimean Tatar existence.

A world war is an international conflict that involves most or all of the world's major powers. Conventionally, the term is reserved for the two major international conflicts that occurred during the first half of the 20th century: World War I (1914–1918) and World War II (1939–1945). Some historians have also characterized other global conflicts as world wars, such as the Nine Years' War, the War of the Spanish Succession, the Seven Years' War, the French Revolutionary and Napoleonic Wars, the Cold War and the Global War on Terrorism.

The Axis powers, originally called the Rome–Berlin Axis and also Rome–Berlin–Tokyo Axis, was the military coalition which initiated World War II and fought against the Allies. Its principal members were Nazi Germany, the Kingdom of Italy and the Empire of Japan. The Axis were united in their far-right positions and general opposition to the Allies, but otherwise lacked comparable coordination and ideological cohesion.

The Axis grew out of successive diplomatic efforts by Germany, Italy, and Japan to secure their own specific expansionist interests in the mid-1930s. The first step was the protocol signed by Germany and Italy in October 1936, after which Italian leader Benito Mussolini declared that all other European countries would thereafter rotate on the Rome–Berlin axis, thus creating the term "Axis". The following November saw the ratification of the Anti-Comintern Pact, an anti-communist treaty between Germany and Japan; Italy joined the Pact in 1937, followed by Hungary and Spain in 1939. The "Rome–Berlin Axis" became a military alliance in 1939 under the so-called "Pact of Steel", with the Tripartite Pact of 1940 formally integrating the military aims of Germany, Italy, Japan, and later followed by other nations. The three pacts formed the foundation of the Axis alliance.

Almost every country in the world participated in World War II. Most were neutral at the beginning, but relatively few nations remained neutral to the end. World War II pitted two alliances against each other, the Allies and the Axis powers. It is estimated that 74 million people died, with estimates ranging from 40 million to 90 million dead (including all genocide casualties). The main Axis powers were Nazi Germany, the Empire of Japan, and the Kingdom of Italy; while the United Kingdom, the United States, the Soviet Union and China were the "Big Four" Allied powers.

The countries involved in or affected by World War II are listed alphabetically, with a description of their role in the conflict.

Air warfare was a major component in all theaters of World War II and, together with anti-aircraft warfare, consumed a large fraction of the industrial output of the major powers. Germany and Japan depended on air forces that were closely integrated with land and naval forces; the Axis powers downplayed the advantage of fleets of strategic bombers and were late in appreciating the need to defend against Allied strategic bombing. By contrast, Britain and the United States took an approach that greatly emphasized strategic bombing and (to a lesser degree) tactical control of the battlefield by air as well as adequate air defenses. Both Britain and the U.S. built substantially larger strategic forces of large, long-range bombers. Simultaneously, they built tactical air forces that could win air superiority over the battlefields, thereby giving vital assistance to ground troops. The U.S. Navy and Royal Navy also built a powerful naval-air component based on aircraft carriers, as did the Imperial Japanese Navy; these played the central role in the war at sea.