Peace of Constance
The Peace of Constance of 1183 was signed in the city of Konstanz by the Hohenstaufen emperor Frederick Barbarossa and representatives of the Italian Lombard League. This six-year armistice established a new relationship between the imperial authority and the Lombard territories, replacing a previously aggressive stance with looser mutual obligations of feudal suzerainty.
The agreement confirmed the 1177 Treaty of Venice. The cities in the Kingdom of Italy retained several regalia of local jurisdiction over their territories and had the freedom to elect their own councils and to enact their own legislation, as well as to keep their Lombard League alliance. The territories, on the other hand, was required to make their own concessions and these include an oath of fealty to the Holy Roman Emperor taken by their consuls and they must receive the investiture from him. Imperial judges had the prerogative to judge appeals and some districts in Italy were placed under direct Imperial administration. The cities also retained civil and criminal jurisdiction while the appellate jurisdiction was in the imperial hands. The consuls were only allowed to render final verdicts in crimes that involve sums of less than twenty-five pounds of gold.
A commentary about the agreement by Baldo degli Ubaldi published in his Commentaria in usus feudorum identified the capability attributed to the emperor to break aspects of it because his oath was considered temporary. However, there was no attempt to infringe the conditions of the compact on the part of the crown during the 67-year reign of the house of Hohenstaufen.
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.
- Or "Second Treaty of Constance." The first was made in 1153.
- Kleinhenz, Christopher (2017). Routledge Revivals: Medieval Italy (2004): An Encyclopedia, Volume 1. Oxon: Routledge. p. 249. ISBN 9781138063266.
- Witt, Ronald (2012). The Two Latin Cultures and the Foundation of Renaissance Humanism in Medieval Italy. Cambridge: Cambridge University Press. p. 234. ISBN 9780521764742.
- Law, John (2016-12-05). Communes and Despots in Medieval and Renaissance Italy. London: Routledge. ISBN 9781351950350.
- de Sismondi, Jean Charles Leonard (2008). A History of the Italian Republics. Cabin John, Maryland: Wildside Press LLC. p. 49. ISBN 9781434460646.
- G. Raccagni. 'Il diritto pubblico, la pace di costanza e i <<libri iurium>> dei comuni lombardi', in D. Quaglioni- G. Dilcher (eds), in Gli inizi del diritto pubblico, 2, da Federico I a Federico II (Bologna-Berlin, 2008) 309-40. 
- G. Raccagni. 'The teaching of rhetoric and the Magna Carta of the Lombard cities: the Peace of Constance, the Empire and the Papacy in the works of Guido Faba and his leading contemporary colleagues', Journal of Medieval History, 39 (2013), 61-79. 
- Norwich, John Julius. The Kingdom in the Sun 1130-1194. Longmans: London, 1970.