Partisan dispositions around Drvar

Apart from Partisan headquarters and related organisations in and around Drvar, there were between 12,000 and 16,000 Partisans in the area of operations that would be subject to the ground assault by XV Mountain Corps. Near Drvar were elements of the 1st Proletarian Corps commanded by Koča Popović; this corps consisted of the elite 1st Proletarian and 6th Lika Proletarian Divisions, the Corps headquarters being located in the village of Mokronoge, 6 km (3.7 mi) east of Drvar.^[9] Its subordinate formations were further away, the 6th Lika Proletarian Division west of Drvar, and the 1st Proletarian Division deployed in the area around Jajce and Mrkonjić Grad, some 50 km (31 mi) east of Drvar.^[10] The nearest large Partisan formation to Drvar was the 3rd Lika Proletarian Brigade of the 6th Lika Proletarian Division based in the Resanovci and Trubar villages some 10 km (6 mi) south and southwest of Drvar.^[11]

In the wider area of operations were the Partisan 5th Corps commanded by Slavko Rodić and the 8th Corps commanded by Vlado Ćetković. The 5th Corps was deployed to the northeast and northwest of Drvar with its headquarters south of the Mrkonjić Grad–Ključ road, and the 8th Corps was positioned to the southeast with its headquarters in the mountains between the Glamoč and Livno valleys. Importantly for the coming battle, the 4th Krajina Division of the 5th Corps was deployed between Bihać and Bosanski Petrovac.^[12] Two brigades of the 4th Krajina Division and one brigade from the 39th Krajina Division formed a defensive arc north of Drvar, running from Bihać through Krupa to Sanski Most.^[10] The 9th Dalmatian Division of the 8th Corps was deployed to the south between Livno and Bosansko Grahovo.^[13]

German intelligence

Three German intelligence organisations attempted to determine the location of Tito's headquarters and the disposition of Partisan forces in Drvar.^[14] The first of these was the Benesch Special Unit of Section II of the Abwehr (the Wehrmacht intelligence service), some members of which had been involved in identifying Tito's presence in the town of Jajce prior to the German offensive to retake the town. The Benesch Special Unit was part of the Brandenburg Division, and was staffed by ethnic Germans who spoke local languages. The unit had many contacts with both the Chetniks and the Ustaše Militia, and had been tracking Tito since October 1943. Leutnant^{[lower-alpha 2]} Kirchner of that unit had been responsible for locating Tito before the re-capture of Jajce, and he established a patrol base near Bosansko Grahovo. He got very close to the Drvar cave, and located the Allied military missions, but despite German radio intercepts confirming that Drvar was the site of Tito's headquarters, Kirchner was unable to pinpoint the cave as the location of the headquarters. Kirchner was attached to the 500th SS Parachute Battalion for the operation.^[15]

The second intelligence organisation was FAT (Front Reconnaissance Troop) 216 of Section I of the Abwehr. FAT216, commanded by Leutnant Zavadil, was also attached to the 500th SS Parachute Battalion, but did not contribute much to the intelligence used to plan the raid.^[16]

On Adolf Hitler's orders, SS-Sturmbannführer^{[lower-alpha 3]} Otto Skorzeny of the Sicherheitsdienst (SD, the intelligence branch of the SS), who had commanded the operation to rescue Mussolini in September 1943, was independently involved in intelligence gathering in the lead-up to the raid.^[17] Skorzeny acted on behalf of the SD, and after obtaining information from a Partisan deserter that pinpointed Tito's headquarters at the cave, he proposed a plan to infiltrate Drvar with a small group of soldiers to assassinate Tito.^[18] Skorzeny soon discovered that the plan to eliminate Tito had been compromised, and had nothing further to do with the operation. It appears that he did not pass on the useful intelligence he had gathered to SS-Hauptsturmführer^{[lower-alpha 4]} Kurt Rybka, the commander of the 500th SS Parachute Battalion, who was responsible for planning the critical airborne aspects of the operation.^[19] Largely due to interservice rivalry and competition,^[16] the three organisations did not share the intelligence they gathered, which had a significant effect on the tactical planning and execution of the operation.^[20] The Germans found forged documents that stated 25 May was Tito's birthday and therefore planned the attack for that day.^[21]

Partisan intelligence

The Partisans had an effective intelligence network. They had been aware of the presence of the 500th SS Parachute Battalion in Yugoslavia for some time, and of the general threat of an airborne assault for over six months. They may have become aware of the isolation of the 500th SS Parachute Battalion or the concentration of transport aircraft and gliders at Zagreb and Banja Luka over a month before the operation. The Partisans also managed to capture the deserter that Skorzeny had interrogated. As a result of these early indicators of an attack, Tito's main headquarters was relocated to another cave near the village of Bastasi, 7 km (4.3 mi) west of Drvar. Tito then used the Drvar cave during the day, but returned to the Bastasi cave at night. As a further precaution, elements of the 6th Lika Proletarian Division were moved closer to Drvar.^[22]

On 23 May 1944, a single German Fieseler Fi 156 reconnaissance aircraft flew several parallel runs up and down the Una valley over Drvar at around 600 m (2,000 ft);^[23] activity consistent with conducting aerial photography.^[24] The aircraft paid particular attention to the villages of Prinavor and Trninić Brijeg where the British military mission and American military personnel were located. This was observed by Street, the acting commander of the British military mission, who assumed it was spotting for a bombing raid and advised both Tito and the Americans. Both Allied missions moved their locations as a result.^[25]

Despite the intelligence received and observations made by the British, the Partisans appear to have been quite complacent about the threat; Tito's chief of staff, Arso Jovanović, swore that "a German attack was impossible". The most obvious indicator that Tito was unaware of the imminent attack is that he remained at the Drvar cave overnight on the evening of 24 May, following a celebration, instead of returning to Bastasi.^[26]

Through Ultra intercepts of German signal traffic, the British had become aware that the Germans were planning an operation codenamed "Rösselsprung". However, the information available did not include where the operation would occur or what its objectives might be.^[24]

500th SS Parachute Battalion

Rybka received an outline of the operation on 20 May, and more details the following day. He realised that the gliders and transport aircraft would be insufficient for the whole of the 500th SS Parachute Battalion to be delivered to Drvar in one lift, so he came up with a plan involving two waves. The first wave of 654 troops would conduct the assault at 07:00 and a second wave of 220 troops would follow about five hours later. Critically, the intelligence he was given regarding the suspected location of Tito's headquarters (codenamed "Citadel") was that it was in or near a cemetery on high ground southwest of the centre of Drvar, nearly 2 km (1.2 mi) from Tito's actual headquarters cave. This would have far-reaching effects on the planning and execution of the assault.^[33]

Rybka's plan for the first wave called for the insertion of 314 parachute troops in three groups (Red, Green and Blue) to secure the town, and another 354 troops in six glider-borne assault groups to carry out specific tasks. The glider-borne group tasks were:^[34]

• Panther Group (110 soldiers) – capture "Citadel" and destroy Tito's headquarters – to land at the cemetery
• Greifer (Grabber) Group (40 soldiers) – destroy the British military mission in the village of Prnjavor 2 km south of Drvar on the road to Bosansko Grahovo
• Stürmer (Stormer) Group (50 soldiers) – destroy the Soviet military mission between the centre of Drvar and the Unac river
• Brecher (Breaker) Group (50 soldiers) – destroy the American military mission in the village of Trninić Brijeg 2 km south of the centre of Drvar
• Draufgänger (Daredevil) Group (70 soldiers including members of the Brandenburg Division, the Abwehr officer Lieutenant Zavadil and some collaborationist Chetniks) – capture the crossroads (codenamed "Western Cross") immediately to the west of Drvar including a nearby suspected communications facility
• Beißer (Biter) Group (20 soldiers) – seize an outpost radio station to the south of Prnjavor then assist the Greifer Group

The second wave of 220 troops based on the training company of the 500th SS Parachute Battalion was to insert by parachute at midday.^[34]

Rybka does not appear to have planned for any significant contingencies such as errors in the intelligence on the location of Tito's headquarters. His only known contingency plan was that he would fire a red signal flare to order all available forces to converge on his position for subsequent tasks.^[35]

On 22 May 1944, the 500th SS Parachute Battalion was transported to airfields at Nagy-Betskerek (Zrenjanin), Zagreb and Banja Luka, dressed in Wehrmacht uniforms for security reasons. The troops were not briefed on the operation until a few hours before it was launched. They then linked up with their transport aircraft, including the ten-man Luftwaffe DFS230 gliders that would deliver the glider-borne troops onto their objectives. By 24 May, all preparations for the airborne assault were complete.^[34]

Ground forces

The plan for the ground forces of von Leyser's XV Mountain Corps was for nine separate but coordinated thrusts toward the Drvar–Bosanski Petrovac area from all directions. The groupings and tasks were:^[36]

• The 384th Infantry Regiment of the 373rd (Croatian) Infantry Division (Croatian legionnaires),^[37] with elements of the 2nd Company of the 202nd Panzer Battalion,^[38] referred to as Kampfgruppe Willam after its commander, Oberst^{[lower-alpha 7]} Willam, was to advance east at 05:00 from the village of Srb toward Drvar. Kampfgruppe Willam had the primary responsibility for relieving then taking command of the 500th SS Parachute Battalion in Drvar on 25 May, and was then to attack in the direction of Bosanski Petrovac.
• A battalion group of the 373rd (Croatian) Infantry Division was to set out at 05:00 from Lapac and drive east through Kulen Vakuf to capture the crossroads at Vrtoče. If necessary, they were then to advance northwest toward Bihać to open the road.
• The 92nd Motorised Regiment, with the 54th Reconnaissance Battalion (from the 1st Mountain Division), the 55th Pioneer Battalion (from the 1st Cossack Division),^[39] the 468th Armoured Car Company,^[40] and a regimental group of the 2nd Croatian Light Infantry Brigade was to advance southeast from Bihać and Bosanska Krupa at 05:00 through Vrtoče to capture Bosanski Petrovac as quickly as possible, destroy the Partisans in that location, and occupy the Partisan airfield and supply installations. After capturing Bosanski Petrovac, elements were to be sent toward Drvar to prevent the withdrawal of Partisans along that road and to link up with the 500th SS Parachute Battalion in Drvar.
• A regimental group of the 7th SS Division was to advance west from the area of Mrkonjić Grad, break through Partisan resistance east of the Sana and then advance on a wide front to block escape routes east out of Drvar. Part of this group was to advance from Jajce along the rail line and roads through Savici to reach their objective, the area around Mliniste power station.
• An ad hoc Kampfgruppe Panzergrenadier Sturmbattalion consisting of officer cadets,^[41] with 1st Company of the 202nd Panzer Battalion,^[40] under the command of the 7th SS Division, was to advance from Banja Luka toward Ključ to seize the crossing point across the Sana utilised by the Partisans.
• The 105th SS Reconnaissance Battalion with an additional panzer company was to advance from Livno and occupy any Partisan supply installations in the Livno Valley, and prevent any Partisan withdrawal to the south of Drvar by attacking through Bosansko Grahovo toward Drvar.
• The 369th Reconnaissance Battalion of the 369th (Croatian) Infantry Division (Croatian legionnaires), under the command of the 105th SS Reconnaissance Battalion, was to advance from Livno up the Glamoč Valley against Partisan forces withdrawing from Drvar to the southeast.
• The 1st Regiment of the Brandenburg Division, along with the collaborationist Chetnik Dinara Division of Momčilo Đujić,^[42] were to advance from Knin toward Bosansko Grahovo and conduct special operations against Partisans in the Prekaja-Drvar area.

Airborne assault and initial response

The 500th SS Parachute Battalion began to parachute and glide onto their objectives at 07:00, most parachutists and glider pilots being able to land relatively close to their targets despite the smoke and dust from the bombing. Some gliders landed significantly off course, including one that landed in front of the Bastasi cave 7 km to the west of Drvar, and several that landed in a locality named Vrtoče near Drvar (not to be confused with Vrtoče between Bihać and Petrovac, which was on the axis of advance of the 92nd Motorised Regiment). The occupants of the glider that landed in Bastasi were immediately killed by members of the Tito Escort Battalion guarding the cave, and the occupants of the gliders at Vrtoče had to fight their way toward Drvar.^[33] After landing, the first wave of the 500th SS Parachute Battalion quickly gained control of Drvar.^[44]

Panther Group supported by Red Group overcame minimal resistance at the cemetery and Rybka established his headquarters behind the cemetery walls, but there was no sign of Tito or his headquarters. Greifer Group and Brecher Group were also unsuccessful as the British and American groups had moved following the aerial reconnaissance on 23 May. Parts of Stürmer Group landed their gliders in a field immediately south of the Drvar cave and came under fire from members of the Tito Escort Battalion on the high ground in the area of the cave. The Draufgänger Group landed their gliders at the "Western Cross", then assaulted a building they believed was the Partisan communications centre. The building was actually the office of the Communist Party of Yugoslavia Central Committee, who resisted fanatically until the building was levelled using satchel charges. Both Blue Group and Green Group, consisting of parachute troops that landed in the eastern part of Drvar where most of the population lived, were also engaged in heavy fighting. The SKOJ had just finished a conference in Drvar, and many of the delegates were still staying in the town. Many youths took up whatever arms they could obtain and commenced fighting the parachutists who were attempting to establish a cordon on the eastern side of the town.^[45]

About 2 km further east on the road to Mokronoge was a Partisan officer training school with about 130 students. On hearing the fighting from the direction of Drvar, the students marched west initially armed with only pistols and a few rifles. They split into two groups, a smaller group that crossed the Unac and advanced west along the railway line on the ridge leading toward Tito's cave, and a larger group that collected arms and ammunition from several stray canisters of German equipment dropped by parachute. The larger group of students attacked Green and Blue Groups from the east around 08:00, suffering severe casualties, but maintained continuous pressure on the German flank. About 09:00, the Germans had largely secured Drvar, and the available troops went from house to house, armed with photographs of Tito, brutally questioning the civilians they could find. Soon after this commenced, Rybka realised that Partisan resistance was concentrated to the north in the vicinity of the cave. He, therefore, fired the red signal flare to rally his troops for an assault in that direction.^[46]

Assault on Tito's cave and the Partisan counterattack

At about 10:30, Rybka launched a frontal attack across the Unac supported by at least one MG42 machine gun firing into the mouth of the cave. The Germans reached the base of the hill, fifty metres from the cave, but suffered severe casualties in the assault. They were also running low on water.^[46] Before this attack, Tito and around 20 staff had taken refuge in the cave.^[24]

While Rybka was assembling his troops for this attack, surrounding Partisan forces were rushed toward Drvar. Three battalions of the 3rd Lika Proletarian Brigade of the 6th Lika Proletarian Division approached from the southeast. One battalion attacked the German position at the cemetery while the other two swung around to strike the Germans from the west.^[47]

About 11:15, after Rybka's first attack had been defeated, Tito and the small group gathered with him escaped from the cave.^[48] There was a platform at the mouth of the cave, and they climbed down a rope through a trapdoor in the platform, although the panic displayed by Tito's mistress Davorjanka Paunović (codenamed "Zdenka") and his dog Tigar caused some delays. The party split up and following a creek leading away from the Unac, the small groups climbed the heights to the east and withdrew toward the village of Potoci.^[24]

Second German attack and withdrawal

The second wave of parachute troops was dropped in two groups to the west of the cemetery at about midday. The drop zone was within fields of fire of the Partisans to the west of Drvar, and the paratroops suffered many casualties during the drop. Collecting the remainder, Rybka mounted a second attack, but the pressure on his flanks was too heavy, and the assault again failed. Fighting continued throughout the afternoon with both sides taking heavy casualties.^[48]

In the late afternoon, Rybka ordered his forces to withdraw to the area of the cemetery where he formed a defensive perimeter. During the withdrawal, at least one group of troops was cut off and killed. About 18:00, Rybka was wounded by a grenade blast and was later evacuated with other casualties in the light aircraft intended to carry away Tito after his capture. Roughly at the same time, his Partisan counterpart in Drvar, Milan Šijan, the commander of the 3rd Lika Proletarian Brigade, was also wounded by German machine gun fire.^[49] By 21:30, the Germans had consolidated their position in the cemetery, although they were completely surrounded by the Partisans. During the night, the 3rd Lika Proletarian Brigade attacked the cemetery, with the 1st Battalion of the 3rd Brigade of the 9th Dalmatian Division reinforcing the assault. At 03:30 on 26 May, the final Partisan attack was launched against the cemetery, breaching the walls in several places, but the paratroopers held on.^[50]

Ground force assault and Partisan withdrawal

Although its total strength was estimated at 185,500 men in late May 1944,^[51] the 2nd Panzer Army was not able to rally more than 16,000 troops for Operation Rösselsprung due to ever-increasing Partisan activity throughout the country. The Germans had to rely on special forces and improved tactics.^[52] The Partisans defended the territory they controlled with significant demolition and mining of roads. Roadblocks were manned by patrols and smaller detachments, whose task was to hold off the enemy until reinforcements arrived.^[53] During Operation Rösselsprung, the Germans rendered these tactics ineffective by combining strong and fast motorised columns with adequate pioneer support. This combination was especially successful for the column led by the 92nd Motorised Regiment.^[54] The second German tactical innovation was the employment of five reconnaissance battalions for independent operations deep inside Partisan-controlled territory.^[55]