Resistance activity in German-occupied France increased significantly in 1944 after the Allied landings in Normandy. Various Maquis units staged uprisings throughout France, capturing villages and fighting the German occupiers. German units feared the imminent Allied landing in Southern France and ramped up anti-partisan operations to recapture and control the French countryside. One of the planned offensives was Operation Treffenfeld, a large-scale offensive aimed at destroying the French resistance of the Maquis de l'Ain et du Haut-Jura. This group had been active in the Ain department for years and had its stronghold around the city of Oyonnax. They conducted widespread sabotage actions against the German infrastructure in the region, and German efforts had been mostly unsuccessful at nullifying the threat.