operation kopaonik was part of a larger plan of the axis forces to disarm chetnik units. the military commander in serbia prepared a list of 24 chetnik officers to be arrested by the 7th ss volunteer mountain division prinz eugen, one of them being keserović. keserović was probably the most active commander of mihailović's chetniks in serbia. this operation was the first large-scale engagement of the 7th ss volunteer mountain division prinz eugen under command of artur phleps, who personally commanded the axis forces during operation kopaonik. the ss division had three regiments: two infantry and one artillery regiment. the german forces were also supported by several bulgarian battalions of 1,000 men, and 300 men from the russian protective corps. keserović was informed about the attack and successfully retreated units of his detachment.