'Schwarz' (ii) was a German, Italian, Croat and Bulgarian double operation against the partisan forces of Josip Broz Tito in the north-western part of Montenegro and the south-eastern part of Herzegovina in Axis-occupied Yugoslavia (15 May/16 June 1943).

This operation was known to the partisan forces as the 'Fifth Enemy Offensive'.

The original Axis plan for 1943 called for the 'Weiss' (ii) undertaking ('Weiss I' to 'Weiss III' sub-operations) to destroy the partisan forces in Yugoslavia, and then 'Schwarz' (ii) operation to disarm the Četnik anti-communist Yugoslav forces, led by Colonel Dragoljub 'Draza' Mihailović, in the Italian occupation zone of Yugoslavia. The Četniks were organised within the Italian Milizia Volontaria Anti-Comunista (Voluntary Anti-Communist Militia), but in 'Weiss II' the partisans virtually annihilated the Četniks and broke through into eastern Herzegovina and Montenegro. As a result the planning for 'Weiss III' was terminated and 'Schwarz' (ii) was recast as the means to finish the elimination of the partisans before the implementation of the Allied amphibious assault on the Balkans which, as a result of Allied disinformation measures, the Germans believed to be imminent.

Some of the surviving Četnik units were disarmed during 'Schwarz' (ii), but they offered no resistance to the move and some were even listed by German army as guides. The definitive version of 'Schwarz' (ii) was therefore developed in the spring of 1943 was what became known in Yugoslavia as the Sutjeska Offensive as well as the Fifth Enemy Offensive. This was a joint Axis operation aimed at the complete destruction of the Yugoslav partisans near the Sutjeska river in south-eastern Bosnia. The operation was a failure, and marked a significant turning point in Yugoslav affairs during World War II.

The operation followed immediately after the end of 'Weiss' (ii), which had failed to accomplish the objectives now essayed in 'Schwarz' (ii), namely the crushing of the partisan army and the capture of the communist leader, Tito. Generaloberst Alexander Löhr, the Oberbefehlshaber 'Südost', gathered some 127,000 men for the offensive, this total including German, Italian, Croat and Bulgarian units supported by more than 300 aircraft. Facing this great strength was a total of just 18,000 partisans organised in 16 brigades.

The Axis order of battle included SS-Gruppenführer und Generalleutnant der Waffen-SS Artur Phleps’s 7^th SS Gebirgsdivision 'Prinz Eugen' in the area of Ljubuski and Siroki Brijeg, where its positions were taken over by Generalleutnant Emil Zellner’s 373^rd Division (kroatische), Generalleutnant Walter Stettner Ritter von Grabenhofen’s 1^st Gebirgsdivision and parts of Generalmajor Alexander von Pfuhlstein’s Division 'Brandenburg' in Mojkovac, Kolasin, Andrijevica and Berane, Generalleutnant Fritz Neidholdt’s 369^th Division (kroatische) in the area of Foča, Ustikolina and Gorazde except for significant detachments at Prijepolje and Bistirica, Generalleutnant Josef Kübler’s 118^th Jägerdivision (1/750^th Jägerregiment and 2/750^th Jägerregiment at Foča, 2/738^th Jägerregiment and 3/738^th Jägerregiment at Konjic, and other elements of the division in the area to the north of Trnovo), the reinforced 724^th Jägerregiment of Generalleutnant Hartwig von Ludwiger’s 104^th Jägerdivision at Prijepolje and Bodarevo, Generale di Brigata Lorenzo Vivaldi’s Italian 1a Divisione alpina 'Taurinense' at Pljevlja and Prijepolje, Generale di Brigata Silvio Bonini’s Italian 19a Divisione montagna 'Venezia' at Berane, Bijelo Polje and Kolasin, Generale di Divisione Licurgo Zannini’s 23a Divisione montagna 'Ferrara' at Nikisić Danilovgrad, Generale di Divisione Giuseppe Amico’s Italian 32a Divisione montagna 'Marche' at Mostar, Stolac and Metković, Generale di Brigata Giuseppe Adami’s Italian 151a Divisione da occupazione 'Perugia' at Grahovo and Vilusi, Generale di Brigata Luigi Gherzi’s Italian 154a Divisione da occupazione 'Murge' at Bileća, Trebinje and Dubrovnik, Pukovnik Stjepan Gasčić's Croat 4^th Jäger Brigade at Vrelo Bosne, and the Bulgarian 61^st Regiment and 63^rd Regiment at Mokra Gora under command of the 369^th Division.

The partisan order of battle comprised the 1^st Division headquartered in Potrk some 1.8 miles (3 km) to the south-west of Sahović, with the 1^st Proletarian Brigade round Mojkovac and Bijelo Polje, the 3^rd 'Krajina' Brigade round Mojkovac and Bijelo Polje and the 3^rd 'Sandzak' Brigade round Mijajlovica and Jabuka; the 2^nd Division headquartered in Boan to the west of Kolasin with the 7^th 'Krajina' Brigade, the 4^th Proletarian Brigade (less its 3^rd Battalion) in Bistrica some 4.3 miles (7 km) west of Kolasin, and the 2^nd 'Dalmatian' Brigade; the 3^rd Division with the 10^th 'Herzegovina' Brigade along the line between Avtovac and Goransko, the 2^nd Proletarian Brigade with its 1^st and 2^nd Battalions along the line between Niksić and Javorak, the 5^th 'Montenegro' Brigade (less its 2^nd and 4^th Battalions) along the line between Niksić and Savnik, the 1^st 'Dalmatia' Brigade holding Niksić Zupa, and the 3/4^th Proletarian Brigade and the 2 and 4/5^th 'Montenegro' Brigade round Bioča; the 7^th Division headquartered at Čurevo; the 'Drina' Operational Group on the Foča, Ustikolina and Gorazde front with its headquarters in Boan and controlling the 2^nd Proletarian Brigade (3^rd and 5^th Battalions round Crni Vrh to the south of Foča, and 4^th Battalion at Sćepan Polje), the 'Majevica' Brigade (1^st Battalion in the region of Ifsara, and 2^nd and 3^rd Battalions in the region of Krusica), and the 6^th 'Bosnia' Brigade (1^st and 2^nd Battalions round Crni Vrh near Čajnića, and Ilisiji, and 3^rd Battalion to the south of Čajnića); there was also the 3^rd 'Dalmatia' Brigade, probably under command of the 1^st Division, approaching from Pljevalja to Meljak and Kosanica.

After a period of troop concentration and initial advance from 15 May, the Axis offensive started on 20 May 1943. The Axis troops used the advantage of better starting positions to encircle and isolate the partisans in the Durmitor mountain area, located between the Tara and Piva rivers in the mountainous areas of northern Montenegro, and then assaulted them over a period of one month in an intense battle fought over very bleak and inhospitable land. The partisan forces suffered severely for lack of food and medical supplies.

In accordance with Adolf Hitler’s express instruction, Löhr ordered the merciless annihilation of partisans and exemplary brutality to any and all civilians. The Axis troops, who were almost exclusively German in the case of front-line units, advanced to tighten the encirclement as the partisan forces manoeuvred in an effort to find any weak part in the German cordon. After a month of severe and dramatic clashes in wild mountains, the partisan forces succeeded in breaking out of the encirclement across the Sutjeska river through the lines of Generalleutnant Hans Johann Fortner’s 118^th Jägerdivision, Generalleutnant Hartwig von Ludwiger’s 104^th Jägerdivision and Generalmajor Fritz Niedholdt’s 369^th Division (kroatische) on the north-western edge of the encirclement and then moved toward eastern Bosnia. This breakthrough was neither painless nor complete: three brigades and the partisans' central hospital with more then 2,000 wounded remained inside the circle. The Germans killed all the wounded as well as the hospital’s unarmed personnel.

On 9 June a bomb fell near the leading group, killing a British liaison officer and Tito’s dog, the latter jumping at Tito and saving his life, though the partisan leader was wounded in the arm. The situation did not appear good for the partisans but, eager to defeat the Axis forces and bent on survival, the partisans twice broke the German and Italian lines during the following week. Eventually the partisans managed to escape the Axis encirclement, though only at the cost of 6,391 persons out of the strength of about 19,700 they had possessed at the beginning of the Axis offensive. The Germans thus managed to inflict severe casualties, perhaps more than 33%, on the main strength of the partisan forces in this region, but despite their considerable efforts they did not succeed either in destroying the partisans' military capability or in undermining their popularity and political influence.

Immediately after it break-out, the same partisan operational group immediately continued with its offensive plans and cleared the Axis garrisons of Vlasenica, Srebrenica, Olovo, Kladanj and Zvornik in eastern Bosnia during the following 20 days.

In other parts of Yugoslavia, outside the scope of 'Schwarz' (ii), the partisan movement grew even more rapidly in numbers and success. The Battle of the Sutjeska River became a symbol of the partisans' self-sacrifice, capacity to endure extreme privation, and moral firmness. One of the more senior German field commanders, General Rudolf Lüters commanding the XV Gebirgskorps, in his final report admitted that the partisans were 'well organised, skilfully led and possessed a combat morale so high it was hard to believe'.

When Italy signed an armistice with the Allies, effective from 9 September 1943, Germany and her surviving allies were never again able to gather enough troops to mount an offensive of similar size in Yugoslavia, although they did come close to capturing Tito in Drvar during the 'Rösselsprung' (ii) operation of May 1944.

The 'Sixth Enemy Offensive' was a series of operations undertaken by the Germans and the Ustase after the capitulation of Italy in September 1943 as an attempt to secure the Adriatic coast, and took place through the autumn and winter of 1943/44.