Nazım Pasha abandoned Goltz Pasha's defensive (and probably realistic) doctrine and, though the Ottoman army had severe problems in mobilizing its troops (assembling fewer than half of the expected 600,000 troops), developed a bold offensive plan, including offensive operations on both fronts. Because the Serbian army was, after its defeat in the Serbo-Bulgarian War, considered a weaker opponent even by Western observers, Nazım Pasha planned to attack it first, and render it operationally incapable.
Nazım Pasha abandoned Goltz Pasha's defensive strategy, which was likely sound given the Ottoman army's limited manpower (fewer than half of the expected 600,000 soldiers). He then devised a bold offensive plan that involved operations on both fronts.  The Serbian army, weakened after its defeat in the Serbo-Bulgarian War, was seen as an easy target by Western observers, and Nazım Pasha planned to attack it first to cripple it.