Seventh Enemy Offensive - Partisan Intelligence

Partisan Intelligence

The Partisans had their own highly effective intelligence network. They had been aware of the presence of the 500th SS Parachute Battalion in Yugoslavia for some time, and had been aware 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 for over a month before the operation, or the concentration of transport aircraft and gliders at Zagreb and Banja Luka. One of the reasons Skorzeny believed the operation had been compromised was the recapture by the Partisans of a deserter he had interrogated. As a result of these early indicators of an attack, Tito's main headquarters had been relocated to another cave near the village of Bastasi, seven kilometres west of Drvar. Tito then used the Drvar cave during the day, but returned to the Bastasi cave at night. In addition to this precaution, elements of the 6th Proletarian Division were moved closer to Drvar.

On 23 May 1944, a single German Fieseler Storch reconnaissance aircraft flew a number of parallel runs up and down the Una valley over Drvar at 2,000 feet (610 m); activity consistent with conducting aerial photography. 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 Lieutenant Colonel Street, the acting commander of the British military mission, who assumed it was spotting for an bombing raid and advised both Tito and the Americans. Both Allied missions moved their locations as a result.

Despite the intelligence received and observations made by the British, the Partisans appear to have been quite complacent about the threat, with Tito's chief of staff, Arso Jovanović swearing 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 1944, following his birthday celebrations, instead of returning to Bastasi.

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