Peter I of the Serra family, was the eldest son and successor of Barisone II of Arborea

Barisone II of Arborea

Barison II or Barisone II was the giudice of Arborea, a kingdom of Sardinia, from 1146 to 1186. He was the son of Comita II and Elena de Orrubu. His reign was groundbreaking in Sardinian history...

, reigning from 1186 to his death. His mother was Barisone's first wife, Pellegrina de Lacon. He was crowned King of Sardinia, the title his father had used, with the support of a majority of the Arborean nobility.

Immediately after his father's death, he was opposed by his nephew Hugh

Hugh I of Arborea

Hugh I Giudici of Arborea from 1185 CE until his death in 1211 CE. Hugh was the son of Ispella di Serra and Hugh I of Bas. He was a grandson -through his mother- of Barisone II of Arborea...

, the son of Hugh I of Bas and Ispella, Peter's half-sister, the elder daughter of Barisone by his second wife, the Catalan

Catalan people

The Catalans or Catalonians are the people from, or with origins in, Catalonia that form a historical nationality in Spain. The inhabitants of the adjacent portion of southern France are sometimes included in this definition...

 Agalbursa

Agalbursa

Agalbursa , born 1148/55, died after 1186; was the daughter of Ponce de Cervera, viscount of Bas , and Almodis, daughter of Raymond Berengar III of Barcelona...

. Agalbursa had the support of Alfonso II of Aragon

Alfonso II of Aragon

Alfonso II or Alfons I ; Huesca, 1-25 March 1157 – 25 April 1196), called the Chaste or the Troubadour, was the King of Aragon and Count of Barcelona from 1164 until his death. He was the son of Ramon Berenguer IV of Barcelona and Petronilla of Aragon and the first King of Aragon who was...

, but she died soon after instigating the war between her grandson and Peter. Peter was supported by the Republic of Pisa

Republic of Pisa

The Republic of Pisa was a de facto independent state centered on the Tuscan city of Pisa during the late tenth and eleventh centuries. It rose to become an economic powerhouse, a commercial center whose merchants dominated Mediterranean and Italian trade for a century before being surpassed and...

, while Hugh had the backing of the Republic of Genoa

Republic of Genoa

The Most Serene Republic of Genoa |Ligurian]]: Repúbrica de Zêna) was an independent state from 1005 to 1797 in Liguria on the northwestern Italian coast, as well as Corsica from 1347 to 1768, and numerous other territories throughout the Mediterranean....

. In 1189, however, Peter made peace with Genoa and swore fealty to the Republic salva domini pape fidelitate. In 1192, a compromise was finally reached at Oristano

Oristano

Oristano is a town and comune, capital of the Province of Oristano, on the island of Sardinia, Italy. It has approximately 32,500 inhabitants.Its economy is mainly based on fishing, agriculture and, to a certain extent, tourism.-History:...

 whereby Arborea was divided between Peter and Hugh (Treaty of Oristano).

In the late 1190s, Constantine II of Logudoro and his son Comita III

Comita III of Torres

Comita III was the giudice of Logudoro, with its capital at Torres, from 1198 until 1218. He was the youngest of four sons of Barisone II of Torres and Preziosa de Orrubu...

, allies of Genoa, warred with Peter, who was under the protection of William I of Cagliari

William I of Cagliari

William I was the giudice of Cagliari from 1188 to his death.William was one of the greatest of medieval Sardinian giudici...

. Comita eventually sued for peace with Pisa and abandoned his claims over Arborea in exchange for the castle of Goceano

Goceano

The Goceano is a historical and geographical region of center-north of Sardinia island, Italy.It covers a surface of 480 km² and has a population of 13,000 inhabitants...

, held thitherto by William. In 1195, William of Cagliari invaded Arborea, imprisoning Peter and besieging Oristano, forcing Hugh to sign a pact ceding his territories and to marry Preciosa, his daughter and a relative of Peter through her mother.

In 1198, William attacked Arborea again and forced Peter to flee to Hugh. William advanced on Oristano and demanded the cession of several frontier castles, including Marmilla

Marmilla

Marmilla is a natural region of southern-central Sardinia, Italy.It is delimited from east and south by the Campidano, from north-west by Monte Arci, from north by the Giara di Gesturi and the Giara di Serri, and from east by the Flumini Mannu....

, which he obtained. William then captured Peter and his son Barisone and imprisoned them in order to control Arborea more directly. He entrusted the government of the giudicato to the bishops, the canons of Oristano, and the majores (major laymen). Pope Innocent III

Pope Innocent III

Pope Innocent III was Pope from 8 January 1198 until his death. His birth name was Lotario dei Conti di Segni, sometimes anglicised to Lothar of Segni....

, in a letter of 11 August, launched an investigation of the church's participation in this usurpation, which Giusto, Archbishop of Arborea, claimed the canons of Oristano had no authority to effect.

Early in 1200, William of Cagliari requested Peter's half of Arborea, which he already controlled, from the pope. Innocent refused. Unbeknownst to the pope, he had made a secret pact with Hugh whereby he retained control not only of Peter's half of Arborea, but also of all the fortresses in the realm.

When Barisone II of Gallura

Barisone II of Gallura

Barisone II was the Judge of Gallura from about 1170 to his death. He was the son of Constantine III. His name appears in acts of 1182 and 1184....

 died in 1203, he left his giudicato under the protection of Pope Innocent, who penned a letter to Biagio, Archbishop of Torres

Biagio, Archbishop of Torres

Biagio was the Archbishop of Torres from 1 December 1202 to his death late 1214 or early 1215.He was originally from the diocese of Nevers. He went to Rome and became a subdeacon and then a papal notary before 1200. By the influence of Pope Innocent III, he was elected to the vacant see of Porto...

, charging him with assuring a smooth succession in Gallura, which meant arranging a marriage for the young heiress Elena

Elena of Gallura

Elena was the daughter and successor of Barisone II of Gallura and was named after her mother of the Lacon family. She ruled Gallura from the death of her father until her own death, though she was eclipsed by her husband after 1207....

. Innocent advised the judges not to interefer with her marriage and to aid Biagio in everything.

Peter died a prisoner in Pisa and his son Barisone inherited his half of Arborea, after being freed from imprisonment to marry William's heiress, Benedetta

Benedetta of Cagliari

Benedetta was the daughter and heiress of William I of Cagliari and Adelasia, daughter of Moroello Malaspina. She succeeded her father in January or February 1214....

. His wife had been Bina (1189), mother of his only legitimate son Barisone (1190), but they were divorced in 1191. She remarried to Ugo degli Alberti of the Capraia

Capraia

Capraia, called Capraria in ancient times, is an island of Italy, part of the Tuscan Archipelago, off the northwest coast; it is also a comune belonging to the Province of Livorno. It is 62 km from the city of Livorno by sea, and 32 km northwest of the island of Elba; it is slightly...

 family in 1193. Peter also had a bastard son named Gotifred, who died in 1253.

Sources

• Moore, John C. "Pope Innocent III, Sardinia, and the Papal State." Speculum, Vol. 62, No. 1. (Jan., 1987), pp 81–101.