The 'Rijeska Operacija' was a Yugoslav operation by Marshal Josip Broz Tito’s forces to liberate the mountain area around Rijeka, Ilirska and Bistrica in Axis-occupied Yugoslavia (16 April/7 May 1945).
The operation was fought between the formations of General Major Jevrem J. Damjanović's 4th Army and those of General Ludwig Kübler’s LXXXXVII Corps (Generalleutnant Hans von Hösslin’s 188th Gebirgsdivision, Oberst Karl Falkner’s 237th Division and Generalmajor Walter Gorn’s 710th Division).
Within the context of the Yugoslav forces' final operations of World War II, from 16 April the 4th Army advanced from the line linking Crikvenica, Lič, Fuzine and Delnice in direction of Rijeka (Fiume) and Trst (Trieste), and in 22 days of heavy fighting liberated Crikvenica, Kraljevica, Bakar, Opatija, Labin, Buzet, Rijeka, Pula (Pola), Pazin, Umag, Ilirska Bistrica, the islands of Cres, Losinj and Krk, and finally the Croat coast and the Istrian peninsula.
The LXXXXVII Corps was surrounded in area of Ilirska Bistrica, where it capitulated on 7 May. The Yugoslav forces took some 16,000 prisoners including three generals, and most of the corps' surviving matériel. The area of Ilirska Bistrica, Klana, Rijeka and the Učka mountain range was defended by six German, four Italian and two Croat battalions, a regiment of Serb collaborators, and parts of the Četnik 'Dinara' Division, while the area of Postojna, Milje (Muggia), Trieste, Monfalcone and San Pietro (Pivka) was held by Generalleutnant Wilhelm von Hösslin’s 188th Gebirgsdivision with some German and Italian garrison forces and two regiments of Serb collaborators, their equipment including some 150 coastal and anti-aircraft guns.