World War II: A detachment of Chetniks captured the town of Loznica in German-occupied Serbia.

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.

The Chetniks, formally the Chetnik Detachments of the Yugoslav Army, and also the Yugoslav Army in the Homeland and informally colloquially the Ravna Gora Movement, was a Yugoslav royalist and Serbian nationalist movement and guerrilla force in Axis-occupied Yugoslavia. Although it was not a homogeneous movement, it was led by Draža Mihailović. While it was anti-Axis in its long-term goals and engaged in marginal resistance activities for limited periods, it also engaged in tactical or selective collaboration with Axis forces for almost all of the war. The Chetnik movement adopted a policy of collaboration with regard to the Axis, and engaged in cooperation to one degree or another by both establishing a modus vivendi and operating as "legalised" auxiliary forces under Axis control. Over a period of time, and in different parts of the country, the movement was progressively drawn into collaboration agreements: first with the puppet Government of National Salvation in the German-occupied territory of Serbia, then with the Italians in occupied Dalmatia and Montenegro, with some of the Ustaše forces in northern Bosnia, and, after the Italian capitulation in September 1943, with the Germans directly.

The Battle of Loznica involved an attack on the German garrison of that town by the Jadar Chetnik Detachment on 31 August 1941. Following the World War II German-led Axis invasion of Yugoslavia in April 1941, the Kingdom of Yugoslavia was partitioned. At the time, Loznica was part of the German-occupied territory of Serbia, which included Serbia proper, with the addition of the northern part of Kosovo, and the Banat.