World War II: The Axis powers establish the Independent State of Croatia.

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 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, 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 Independent State of Croatia was a World War II–era puppet state of Nazi Germany and Fascist Italy existing from 1941 to 1945. It was established in parts of occupied Yugoslavia on 10 April 1941, after the invasion by the Axis powers. Its territory consisted mostly of modern-day Croatia and Bosnia and Herzegovina, as well as some parts of modern-day Serbia and Slovenia, but also excluded many Croat-populated areas in Dalmatia, Istria, and Međimurje regions.