After the initial apparent victory in Algiers, in April 1957 Bigeard moved the 3e RPC back into the Atlas mountains in pursuit of FLN groups in that province. In May he was in the area near Agounennda to ambush a large force of about 300 djounoud of the FLN group Wilaya 4. This group had already attacked an Algerian Battalion on 21 May causing heavy casualties. From a 'cold' start Bigeard estimated the attacking group's probable route of withdrawal and laid a wide ambush along a valley of 100 km². The ensuing battle and followup lasted from 23 to 26 May 1957, but resulted in eight paras killed for 96 enemy dead, twelve prisoners and five captives released. For this exemplary operation he was nicknamed "Seigneur de l'Atlas" ("Lord of the Atlas mountains") by his boss General Massu.