On May 11, 1944, the Allies launched Operation Diadem which finally resulted in the collapse of the Gustav Line and the capitulation of the German defences along the Winter Line. From May 15-19, the 15th Panzergrenadiers fought a retreating battle through the Aurunci Mountains against the 3rd Algerian Infantry and 4th Moroccan Mountain Divisions of the French Expeditionary Corps, commanded by General Alphonse Juin.