Excerpts from Books and Wikipedia
"As dawn broke on May 29, 1176, the army of the Holy Roman Emperor, Frederick Barbarossa, crossed the Loan River and was met by the 3,500-strong army of the Lombard League, a collection of states that remained loyal to the beleaguered Pope Alexander III. . . . The Lombard victory determined the future political course of Italy. In the resulting Treaty of Venice, Frederick was forced to accept the pope's sovereignty over the Papal States and temporal rights over the city of Rome. Frederick also ended several years of schism in the church by withdrawing his support for the antipope Calixtus III. In addition, a peace treaty was agreed with William II of Sicily, which brought about a period of peace and prosperity for the Sicilian people. After further struggles, Frederick finally gave up his ambition to control the Lombard cities in 1183." [1001 Days]