This was a German operation to ease the partisan pressure on Sarajevo in German-occupied Yugoslavia (16/20 March 1945).
By this time late in the war, the growing strength and capability of the partisan forces of Marshal Josip Broz Tito had been reflected in the renaming of the partisan forces as the Yugoslav army, whose southern forces were now exerting considerable pressure of the German defence of Sarajevo at Jablanica and Trebavić.
General Ernst von Leyser, commander of the XXI Gebirgskorps, decided to launch a counterattack and therefore deployed two regiments of SS-Brigadeführer und Generalmajor der Waffen-SS August Schmidhuber''s 7th SS Gebirgsdivision 'Prinz Eugen' in the area of Hrasnica, Blazuja and Butmir. During night of 16/17 March the Germans started to infiltrate the first elements of the 14th SS Gebirgsjägerregiment over Igman mountain toward Presjenica with the object of attacking the staff, artillery and rear area of the Yugoslav 3rd Division located at Trnovo, and so open the way for an attack into rear of the Yugoslav divisions and brigades holding positions facing Sarajevo. To aid the outflanking movement, a frontal pinning attack was launched by the 964th Festungsbrigade and the Kampfgruppe 'Daniel'. The Igman area is difficult mountain, hill and forested terrain with almost no roads and, at that time, covered by deep snow, and as a result the Yugoslavs, believing it impenetrable, had not covered it and so left a large gap between 5th Brigade of the 3rd Division and right wing of the 29th 'Herzegovina' Division.
Thus the German infiltration remained undetected until 12.00 on 17 March, by which time it had reached the line linking Oblo brdo and Ledići village, pushing aside parts of the 5th Proletarian Brigade, some 5 miles (8 km) south-west of Trnovo, without difficulty and threatening left flank and rear of the 3rd Division. The German advance fought its way through Dujmović, Godinje, Turovi and Tosići toward the road linking Sarajevo and Trnovo. The 14th SS Gebirgsjägerregiment was followed by a sister unit, the 13th SS Gebirgsjägerregiment, which attacked the Yugoslav artillery positions around the village of Umčani, forcing the Yugoslavs to pull back.
During the evening German armour caught up with the Yugoslavs' retreating divisional hospital and rear echelons, but then itself ran into a well-sited anti-tank gun: the first tank was destroyed by the first shell, the wreckage blocking the road for other tanks and allowing the Yugoslav units to retire in good order.
The next days saw the further retreat of the Yugoslav forces. The 3rd Division was partially encircled on Jahorina mountain until it managed to regroup and start to launch counterattacks with the 4th 'Herzegovina' Battalion attacking the Germans in the rear through the Hojte pass.
On 20 March 'Berggeist' was terminated, the Germans pulling back from their exposed position at Trnovo and mining the roads and demolishing bridges as they retreated under attack by the 3rd Division and four 'Herzegovina' battalions supported by corps artillery and the Yugoslav air force’s 1st Squadron. By 24 March the front had been restored to its position at the beginning of 'Berggeist'.
The figures for the Germans casualties have not been found, and the claimed Yugoslav losses were 64 killed, 95 wounded and 19 missing in the 3rd Division, and 15 killed and 60 wounded in the 'Herzegovina' battalions. Although successful in basic terms, 'Berggeist' did not inflict serious losses on Yugoslav army. The 7th SS Gebirgsdivision was then shifted to Vares for 'Osterglocke'.