Italian league that resisted attempts by the Holy Roman emperors to curtail the liberties of the communes of Lombardy in northern Italy in the 12th–13th century.
Founded in 1167, it was backed by Pope Alexander III , who saw it as an ally against Emperor Frederick I Barbarossa . After several military setbacks at the hands of the league, Frederick was forced to grant the Lombard cities communal liberties and jurisdiction under the Peace of Constance. The league again was renewed in 1226 and resisted Frederick II's attempt to reassert imperial power in northern Italy.