This was the Yugoslav operation by the forces of Marshal Josip Broz Tito to liberate Trst (Trieste) and the region round it from occupation by the Axis forces (29 April/1 May 1945).
The operation began with the advance of the main strength of General-pukovnik Peko Dapčević’s Yugoslav 4th Army toward Trieste. The army’s two operational groups advanced along the axes from Ilirska Bistrica to Divača and Trieste, and from Lovran through Istria to Trieste, while the IX Corps advanced over Kras toward Trieste, Tržić (Monfalcone) and Gorica. By 30 April units of the 4th Army had surrounded Trieste and, with concentric attacks and the aid of partisan forces in the city, took Trieste on 1 May after heavy fighting.
In street fighting against units of the German defence, elements of the 20th Division captured the university, military hospital and railway station by direct assault. The 11th Brigade of the 26th ‘Dalmatia’ Division reached coast at the San Marco docks, while the 3rd Brigade of the 43rd Division cleared the Milje peninsula and captured Žavlju. The German stronghold at Opičine was captured on 3 May, and during the first days of May the Yugoslav forces liberated the entire Slovenian littoral, Beneška Slovenia and Istria.
General Ludwig Kübler’s LXXXXVII Corps capitulated on 7 May, and with the advance of the 4th Army’s Motorised Detachment toward Koruška and of the 29th Division and VII Corps toward Ljubljana, the ‘Tršćanska operacija’ was complete after more than 5,200 Germans had been taken prisoner and substantial numbers either killed or wounded.
The Axis troops in the Trieste area were the remnants of various formations and part of the Küstenverteidigungsabschnitt ‘Triest’ (Trieste Coast Defence Sector) local defence force from the Milje (Muđa, Mugga) peninsula to the Soca river. This defensive force had three coastal artillery and two anti-aircraft artillery battalions, five infantry battalions and one mixed battalion, and also numerous naval and army installations. In addition, Generalleutnant Wilhelm von Hösslin’s 188th Gebirgsdivision and Oberst Karl Falkner’s 237th Division of the LXXXXVII Corps were present in Istria, there were several police battalions of the Italian fascist militia, around Gorica there was the 10th SS Polizeiregiment, and David Damjanović’s Srpski Dobrovoljački Korpus (Serb Volunteer Corps) and Vojvoda Momčilo Đujić’s Četnik ‘Dinara’ Division, initially allocated to the task of railway security in Istria, were used in combat around Iliriska Bistrica and sent to Soca.