The battle of San Cesario in August 1229 was the culmination of a civil war between the members of the

Lombard League The Lombard League (; ) was an alliance of cities formed in 1167, and supported by the popes, to counter the attempts by the Hohenstaufen Holy Roman emperors to establish direct royal administrative control over the cities of the Kingdom of It ...

. In the pitched battle,

Modena Modena (, ; ; ; ; ) is a city and ''comune'' (municipality) on the south side of the Po Valley, in the Province of Modena, in the Emilia-Romagna region of northern Italy. It has 184,739 inhabitants as of 2025. A town, and seat of an archbis ...

and its allies defeated

Bologna Bologna ( , , ; ; ) is the capital and largest city of the Emilia-Romagna region in northern Italy. It is the List of cities in Italy, seventh most populous city in Italy, with about 400,000 inhabitants and 150 different nationalities. Its M ...

and its allies.Salimbene, quoted in . The war, which began in 1226, pitted Bologna, supported by

Milan Milan ( , , ; ) is a city in northern Italy, regional capital of Lombardy, the largest city in Italy by urban area and the List of cities in Italy, second-most-populous city proper in Italy after Rome. The city proper has a population of nea ...

and

Piacenza Piacenza (; ; ) is a city and (municipality) in the Emilia-Romagna region of Northern Italy, and the capital of the province of Piacenza, eponymous province. As of 2022, Piacenza is the ninth largest city in the region by population, with more ...

, against Modena, supported by

Cremona Cremona ( , , ; ; ) is a city and (municipality) in northern Italy, situated in Lombardy, on the left bank of the Po (river), Po river in the middle of the Po Valley. It is the capital of the province of Cremona and the seat of the local city a ...

and

Parma Parma (; ) is a city in the northern Italian region of Emilia-Romagna known for its architecture, Giuseppe Verdi, music, art, prosciutto (ham), Parmesan, cheese and surrounding countryside. With a population of 198,986 inhabitants as of 2025, ...

. Bologna's former ally, Reggio, remained neutral. In 1228, Bologna invaded the territory of Modena, but an epidemic forced its withdrawal. In August 1229, Bologna laid siege to the Modenese castle of San Cesario. According to the '' Guelph Annals of Piacenza'', the commune of

sent 174 knights to assist Bologna. According to

Salimbene de Adam Salimbene di Adam (or Salimbene of Parma) (9 October 1221 – 1290) was an Italian Franciscan friar, theologian, and chronicler. Salimbene was one of the most celebrated Franciscan chroniclers of the High Middle Ages. His ''Cronica'' is a fundam ...

, the castle was captured within sight of the armies of Modena, Parma and Cremona. The result was that "one night there was a great fight between them ... and there was a great slaughter of men, footsoldiers and knights, on both sides." The Bolognese were forced to retreat, "leaving their ''carroccio'' and all their equipment in the field". In the aftermath of their victory, the Modenese intended to take the abandoned ''

carroccio A carroccio (; ) was a large four-wheeled wagon bearing the city signs around which the militia of the medieval communes gathered and fought. It was particularly common among the Lombard, Tuscan and, more generally, northern Italian municipali ...

'' back to Modena, but the Parmesans intervened on Bologna's behalf. Salimbene has them saying that "it was not good to do all the harm they could to their enemies, and that" taking the ''carroccio'' "would be an indelible affront and would provoke many evils." As a result, the ''carroccio'' was taken to the Bolognese castle of Piumazzo and returned. One of the victims of the battle was Salimbene's father's first cousin, Berardo Oliverio di Adamo, who fought on the side of Parma. As an honour, his body lay in state before the font of the Parma Baptistery. His obituary in the ''

Chronicon Parmense In historiography, a ''chronicon'' is a type of chronicle or annals. Examples are: * ''Chronicon'' (Eusebius) * ''Chronicon'' (Jerome) *''Chronicon Abbatiae de Evesham'' *'' Chronicon Burgense'' *'' Chronicon Ambrosianum'' *''Chronicon Compostellanu ...

'' calls him "an eloquent judge and a proven soldier" who died "in the battle of San Cesario" and was buried in "the church of Sant'Agata, which is the chapel of the greater church of the city of Parma." According to

Pietro Cantinelli Pietro is an Italian masculine given name. Notable people with the name include: People * Pietro I Candiano (c. 842–887), briefly the 16th Doge of Venice * Pietro Tribuno (died 912), 17th Doge of Venice, from 887 to his death * Pietro II Can ...

, elements of the Bolognese militia mutinied after the retreat.Cantinelli dates these events to 1231. , nn. 22 & 24, places them in 1228 while claiming that the "truce was not broken in 1229". There was a riot and the Palazzo Communale was occupied. The rioters demanded peace and the communal authorities opened negotiations with Modena. Bishop

Enrico della Fratta Enrico is both an Italian masculine given name and a surname, Enrico means homeowner, or king, derived from '' Heinrich'' of Germanic origin. It is also a given name in Ladino. Equivalents in other languages are Henry ( English), Henri ( French), ...

served as one of the Bolognese negotiators. Guala de Roniis mediated. A truce was signed on 11 December 1229 for nine years, although Bologna broke it in 1234. The Bolognese–Modenese war and battle of San Cesario took place while Pope

Gregory IX Pope Gregory IX (; born Ugolino di Conti; 1145 – 22 August 1241) was head of the Catholic Church and the ruler of the Papal States from 19 March 1227 until his death in 1241. He is known for issuing the '' Decretales'' and instituting the P ...

was trying to rally the Lombard League to fight for him against the league's erstwhile enemy, Emperor Frederick II, in the so-called

War of the Keys The War of the Keys (1228–1230) was the first military conflict between Frederick II, Holy Roman Emperor, and the Papacy. Fighting took place in Central Italy, central and southern Italy. The Papacy made strong gains at first, securing the Pap ...

. A comparison of the number of troops committed by the communes to the war against Frederick and the war between themselves indicates how much greater importance they attached to the latter.

Notes

Bibliography

* * * * * * {{refend Conflicts in 1229 Military history of Bologna Military history of Milan History of Modena History of Parma Cremona Piacenza