World War II: The United Kingdom and Canada declare war on Finland in support of the Soviet Union during the Continuation War. Camp X opens in Canada to begin training Allied Secret Agents for the War.

Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over 9.98 million square kilometres (3.85 million square miles), making it the world's second-largest country by total area. Its southern and western border with the United States, stretching 8,891 kilometres (5,525 mi), is the world's longest binational land border. Canada's capital is Ottawa, and its three largest metropolitan areas are Toronto, Montreal, and Vancouver.

Indigenous peoples have continuously inhabited what is now Canada for thousands of years. Beginning in the 16th century, British and French expeditions explored and later settled along the Atlantic coast. As a consequence of various armed conflicts, France ceded nearly all of its colonies in North America in 1763. In 1867, with the union of three British North American colonies through Confederation, Canada was formed as a federal dominion of four provinces. This began an accretion of provinces and territories and a process of increasing autonomy from the United Kingdom. This widening autonomy was highlighted by the Statute of Westminster 1931 and culminated in the Canada Act 1982, which severed the vestiges of legal dependence on the Parliament of the United Kingdom.

Canada is a parliamentary democracy and a constitutional monarchy in the Westminster tradition. The country's head of government is the prime ministerwho holds office by virtue of their ability to command the confidence of the elected House of Commonsand is appointed by the governor general, representing the monarch, who serves as head of state. The country is a Commonwealth realm and is officially bilingual (English and French) at the federal level. It ranks among the highest in international measurements of government transparency, civil liberties, quality of life, economic freedom, and education. It is one of the world's most ethnically diverse and multicultural nations, the product of large-scale immigration from many other countries. Canada's long and complex relationship with the United States has had a significant impact on its economy and culture.

A highly developed country, Canada has the 24th highest nominal per capita income globally and the sixteenth-highest ranking on the Human Development Index. Its advanced economy is the eighth-largest in the world, relying chiefly upon its abundant natural resources and well-developed international trade networks. Canada is part of several major international and intergovernmental institutions or groupings including the United Nations, NATO, the G7, the Group of Ten, the G20, the Organisation for Economic Co-operation and Development (OECD), the World Trade Organization (WTO), the Commonwealth of Nations, the Arctic Council, the Organisation internationale de la Francophonie, the Asia-Pacific Economic Cooperation forum, and the Organization of American States.

The Continuation War, also known as the Second Soviet-Finnish War, was a conflict fought by Finland and Nazi Germany against the Soviet Union from 1941 to 1944, as part of World War II. In Soviet historiography, the war was called the Finnish Front of the Great Patriotic War. Germany regarded its operations in the region as part of its overall war efforts on the Eastern Front and provided Finland with critical material support and military assistance, including economic aid.The Continuation War began 15 months after the end of the Winter War, also fought between Finland and the USSR. Numerous reasons have been proposed for the Finnish decision to invade, with regaining territory lost during the Winter War being regarded as the most common. Other justifications for the conflict included Finnish President Risto Ryti's vision of a Greater Finland and Commander-in-Chief Carl Gustaf Emil Mannerheim's desire to annex East Karelia. Plans for the attack were developed jointly between the Wehrmacht and a faction of Finnish political and military leaders, with the rest of the government remaining ignorant. Despite the co-operation in the conflict, Finland never formally signed the Tripartite Pact, though it did sign the Anti-Comintern Pact. Finnish leadership justified its alliance with Germany as self-defence.

On 22 June 1941, Germany launched an invasion of the Soviet Union. Three days later, the Soviet Union conducted an air raid on Finnish cities, prompting Finland to declare war and allow German troops stationed in Finland to begin offensive warfare. By September 1941, Finland had regained its post–Winter War concessions to the Soviet Union: the Karelian Isthmus and Ladoga Karelia. However, the Finnish Army continued the offensive past the pre-1939 border during the conquest of East Karelia, including Petrozavodsk, and halted only around 30–32 km (19–20 mi) from the centre of Leningrad. It participated in besieging the city by cutting the northern supply routes and by digging in until 1944.In Lapland, joint German-Finnish forces failed to capture Murmansk or to cut the Kirov (Murmansk) Railway, a transit route for Soviet lend-lease equipment. The conflict stabilised with only minor skirmishes until the tide of the war turned against the Germans and the Soviet strategic Vyborg–Petrozavodsk Offensive occurred in June 1944. The attack drove the Finns from most of the territories that they had gained during the war, but the Finnish Army halted the offensive in August 1944.

Hostilities between Finland and the USSR ended with a ceasefire, which was called on 5 September 1944, formalised by the signing of the Moscow Armistice on 19 September 1944. One of the conditions of this agreement was the expulsion, or disarming, of any German troops in Finnish territory, leading to the Lapland War between Finland and Germany.

World War II was concluded formally for Finland and the minor Axis powers with the signing of the Paris Peace Treaties in 1947. This confirmed the territorial provisions of the 1944 armistice: the restoration of borders per the 1940 Moscow Peace Treaty, the ceding of the municipality of Petsamo (Russian: Пе́ченгский райо́н, Pechengsky raion) and the leasing of Porkkala Peninsula to the Soviets. Furthermore, Finland was required to pay US$300 million in war reparations to the Soviet Union, accept partial responsibility for the war and to acknowledge that it had been a German ally.Casualties were 63,200 Finns and 23,200 Germans dead or missing during the war and 158,000 Finns and 60,400 Germans wounded. Estimates of dead or missing Soviets range from 250,000 to 305,000, and 575,000 have been estimated to have been wounded or fallen sick.