Stracin–Kumanovo operation

The Stracin–Kumanovo operation (Bulgarian: Страцинско-Кумановска операция) was an offensive operation conducted in 1944 by the Bulgarian Army against German forces in occupied Yugoslavia which culminated in the capture of Skopje in 1944. With the Bulgarian declaration of war on Germany on September 8, followed by the Bulgarian withdrawal from the area, the German 1st Mountain Division moved north, occupied Skopje, and secured the strategic Belgrade–Nis–Salonika railroad line.

Source: Wikipedia — Stracin–Kumanovo operation (CC BY-SA 4.0)