The Yugoslav plan of defense called for initial resistance along the borders, to gain the time needed to form the primary line behind the Drava, Danube, and Nisava Rivers. This line was supposed to hold for at least three weeks, allowing the main line to be prepared. The main line, utilizing the highlands behind the Sava and Morava Rivers, was expected to hold out for several months. As events turned out, the initial line was rapidly overrun, and the entire defense plan had totally collapsed by the third day of the Axis invasion.

More Yugoslav Army of WWII

Introduction
Infantry and Border Units
Cavalry and Artillery
Mechanized Units and AA
Navy
Air Force (with OOB)
Army OOB
Yugoslavia Map (slow: 75K)