12-я армия
The Yugoslav "coup d'état" led to a sudden change in the plan of attack and confronted the Twelfth Army with a number of difficult problems. According to the 28 March Directive No. 25, the Twelfth Army was to create a mobile task force to attack via Niš toward Belgrade. With only nine days left before their final deployment, every hour became valuable and each fresh assembly of troops took time to mobilise. By the evening of 5 April, the forces intended to enter southern Yugoslavia and Greece had been assembled.