Syrmian Front

The Syrmian Front was an Axis line of defense during World War II. It was established as part of the Eastern Front in late October 1944 in Syrmia and east Slavonia, northwest of Belgrade.

After the Yugoslav Partisans and the Red Army expelled the Germans from Belgrade in the Belgrade Offensive, the retreating Wehrmacht and the Croatian Armed Forces used fortifications to protect the withdrawal of German Army Group E from the Balkans. With help from their Soviet allies, the Partisans, joined by Bulgarian and Italian forces, fought a difficult winter campaign and finally broke through the front on 12 April 1945.

After the Syrmian front was broken, occupied Yugoslavia was liberated.

Source: Wikipedia