The 1st Proletarian Brigade, later the 1st Proletarian Division, was the first brigade-size formation raised by the Yugoslav Partisans during World War II. The unit was one of the elite formations of the National Liberation Army of Yugoslavia. Its combat value was respected by the enemy. Artur Phleps, V SS Mountain Corps commander, in his war journal in 1944 assessed as a serious opponent, very well managed and well trained, who fights like a regular troop.

The Yugoslav Partisans, or the National Liberation Army, officially the National Liberation Army and Partisan Detachments of Yugoslavia, was the communist-led anti-fascist resistance to the Axis powers in occupied Yugoslavia during World War II. Led by Josip Broz Tito, the Partisans are considered to be Europe's most effective anti-Axis resistance movement during World War II.