High Quality Content by WIKIPEDIA articles! The Battle of Casalecchio took place on 26 June 1402 near the town of Casalecchio di Reno, near Bologna. At this battle, a Bolognese army under Giovanni I Bentivoglio opposed Gian Galeazzo Visconti, Duke of Milan, and his allies, the Malatesta of Rimini and the Gonzaga of Mantua. Bologna was aided by Florence in these cities` struggle to halt the expansion of Visconti`s power.