Case White

Case White, also known as the Fourth Enemy Offensive was a combined Axis strategic offensive launched against the Yugoslav Partisans throughout occupied Yugoslavia during World War II. It was one of the most significant confrontations of World War II in Yugoslavia. The offensive took place in early 1943, between 20 January and mid-to-late March. The Axis operation prompted the Partisan Supreme Command to enact its plans to drive toward eastern Herzegovina, Sandžak and Montenegro.In order to do this, Tito formed the so-called Main Operational Group, which eventually succeeded in forcing its way across the Neretva in mid-March 1943, after a series of battles with various hostile formations. Other Partisan formations, the 1st Croatian and 1st Bosnian Corps, managed to evade Axis blows and, despite significant losses, reclaim most of the territory they had held before the beginning of the operation.

Source: Wikipedia