World War II: German troops capture the city of Białystok during Operation Barbarossa.

World War II or the Second World War 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 tried for war crimes.

Białystok is the largest city in northeastern Poland and the capital of the Podlaskie Voivodeship. It is the tenth-largest city in Poland, second in terms of population density, and thirteenth in area.

Operation Barbarossa was the invasion of the Soviet Union by Nazi Germany and several of its European Axis allies starting on Sunday, 22 June 1941, during World War II. More than 3.8 million Axis troops invaded the western Soviet Union along a 2,900-kilometer (1,800 mi) front, with the main goal of capturing territory up to a line between Arkhangelsk and Astrakhan, known as the A–A line. The attack became the largest and costliest military offensive in human history, with around 10 million combatants taking part in the opening phase and over 8 million casualties by the end of the operation on 5 December 1941. It marked a major escalation of World War II, opened the Eastern Front—the largest and deadliest land war in history—and brought the Soviet Union into the Allied powers.