Bulgarian Advance
Just as Fall Gelb could be seen as Germany re-fighting the Schlieffen Plan of the Great War, Bulgaria’s battle plan in Yugoslavia was a similar repeat of the 2nd Bulgarian Army in the Serbian Campaign of 1915.
After their initial advance past the border towards Skopje, the Bulgarian troops had faced stiff resistance from the Yugoslav 3rd Territorial Army as their advance had pushed into the deploying Yugoslav units. The attack along this axis was not through preprepared defensive positions though, and so the use of Bulgarian PZL.43’s for targeted airstrikes was not very effective against the defenders firing from shallow foxholes amongst the trees. But against overwhelming numbers and with no air support of their own the Yugoslav’s were slowly pushed back, and by the evening of the 28th the Bulgarian forces had advanced through the heaviest of the hill country and captured the village of Ginovci. By day three of the assault, the crumbling 3rd Territorial Army was no longer an effective fighting force , while to their north the 5th Army had deployed against a potential attack from northern Bulgaria which had not occurred. Facing minimal resistance Kumanovo was captured on the 30th April.
The advance from Tsarevo Selo met with less Yugoslav resistance with the local units were still in their mobilisation and unprepared for a coherent defence against the assault. But the terrain was even more inhospitable to a motorised advance than that travelled by the Bulgarian northern thrust, and progress was slow. By the evening of the 28th the Bulgarian column had only advanced as far as Vinica, where they regrouped in preparation for a push down the more favourable farmland of the Kočani Valley. Although a defence was made at Shtip it became no more than a delay to the Bulgarian’s advance across the open country of the Ovče Pole, and by the 30th had pushed through Sveti Nikole on the road to Skopje.
The Bulgarian southern assault met only weak resistance once the border fortifications were breached, and although this push was through the Strumica River valley rather than hill country, the Bulgarians found themselves mired in mud and minefields. The advance had only achieved 10 kms by nightfall on the 27th. Early on the 28th the Yugoslavian 21st Infantry Regiment mounted a counter attack from the hills to the north of Shushitsa. The Bulgarians had stayed in the valley and had not probed into the hills, and were taken by surprise while they were in the process of reforming to advance again. Although heavily outnumbered the Yugoslav’s mounted a spirited attack with the aim of blunting and delaying the advance, rather than repelling the invaders. Unexpectedly the Yugoslavian soldiers found themselves supported by 2 Dornier Do 17’s who were independently hitting targets of opportunity from their isolated dispersal airstrips.
Having delivered their warloads the Dornier’s left the battle, and the Bulgarian ground forces soon regained their composure and rallied. With the tide of battle turning, the Yugoslavian troops started pulling back and disengaged from combat and disappeared back into the wooded hills. Too late to effect the skirmish, Bulgarian air support arrived as the Bulgarian column was reforming and the fighters merely flattened the church of Saint George overlooking Shushitsa and shattered Yugoslavian trees, but the 21st Infantry Regiment had already dispersed.
With better conditions and no significant resistance Strumica fell that afternoon, and after consolidating their position in the town the Bulgarian column headed back into the hills to their south to take the site of the historic Bulgarian victory of Kosturino, and closing the Greek border at Gevgelija.
The Yugoslavian defence against the Bulgarians had rapidly collapsed on all axes, with Kavadarci captured on the 30th, as the Bulgarian southern and central columns prepared to unite and assault Skopje. With pressure now on Skopje, Bulgarian bombers attacked the city, striking the civilian population rather than specific military targets.