Excerpts from Books and Wikipedia
"The final Peace of Constance between Frederick Barbarossa, the pope, and the Lombard towns is signed. The various articles of the treaty destroyed the unity of the Empire and Germany and Italy underwent separate developments. [Wikipedia: Timeline of Middle Ages] "The Peace of Constance (25 June 1183) was a privilege granted by Frederick I, Holy Roman Emperor, and his son and co-ruler, Henry VI, King of the Romans, to the members of the Lombard League to end the state of rebellion (war) that been ongoing since 1167. It was a permanent peace that superseded the six-year truce imposed by the Treaty of Venice (22 July 1177). . . . The cities stopped fulfilling their obligations during the long struggle for the Imperial crown that followed the death of Frederick's son Emperor Henry VI in 1197, and the Peace of Constance was at the centre of the new conflict fought between the so-called second Lombard League and Emperor Frederick II between 1226 and 1250. It was celebrated for the rest of the Middle Ages and beyond as the only Imperial recognition of the autonomy of a large group of Italian cities." [Wikipedia]