I seem to recall, that there was a massacre in retaliation for an ambush in a city street by Italian Communist Guerrillas? The Nazi’s were known for their retaliation due to guerrilla activities. Italy was occupied by the Germans after the Italians surrendered. There were still Italian forces in Italy that supported the Germans. The Germans didn’t see the Italians as an enemy. The Italian Communists wanted to play soldiers, and the end result was they were rounded up. The Hague convention wasn’t vague on the treatment of Guerrillas. Like any war, no one wants to see their soldiers in their command killed by enemy partisans, lose a couple of buddies through partisan actions and bad things come out of it. My Lai was a good American example. War is truly hell, and not everyone is able to come out of it with clean hands.
The Fosse Ardeatine massacre of 1943.