The town was attacked by a group of some 300 resistance fighters drawn from the 77th Squadra di Azione Patriotica Brigade "F.lli Manfredi" the 1st and 7th Gruppo di Azione Partigiana squads of the 65th "Walter Tabacchi" Brigade and the "Ciclone" squad of the 121st Garibaldi "A. Luppi" Brigade. They came from resistance groups scattered all across the lower Mantuan province, as well as from Modena and Reggio provinces. Most gathered in secret on the evening of the 19th of December at an out-of-the way rural spot south of the town, Cantonazzo.