Cagliari in Arborea, Judge of Cagliari, master of Arborea in

About 1195 William of Massa defeated Judge Peter of Arborea, captured him with his son Barisone, took Oristano (its cathedral was wrecked) and had himself recognised as ruler of Arborea without the Church's approval (it.wikipedia).

Before early 1200 he made a private pact with the co-judge Hugh of Bas, giving Hugh his daughter Preziosa and half of Arborea as dowry but keeping the main fortresses for himself (DBI). The castles drawn here, Arcuentu and Marmilla, are the Arborean strongholds documented before 1200 (both pledged to Genoa in Barisone I's time and returned in 1192); which castles William's men actually held that winter is not pinned beyond the DBI's 'the main fortresses'.

Who he is

Name: William of Massa (Salusio IV)
Title: Judge of Cagliari, master of Arborea in fact
Since: About 1195 (DBI; English Wikipedia: 1198)
Born: About 1160
Family: Obertenghi of Massa
Confidence: medium

DBI life of William; it.wikipedia Giudicato di Arborea and Giudicato di Cagliari

Overlord

None he admits: Innocent III refuses to approve his rule over Arborea.

What it holds

Custody of Judge Peter I of Arborea and his son Barisone (aged about nine)
The main fortresses of Arborea (not named in the sources used; Arcuentu and Marmilla are the likeliest)
Control of Oristano (taken about 1195; who governs it day to day in 1200 is not pinned)

How it was acquired

Conquest, about 1195.

Allies and rivals

Hugh of Bas (client by pact); the pope and Genoa (opposed).

How things stand that morning

Held by force on 1 January 1200, with Hugh of Bas's consent under the private pact.

Wealth

Arborea's dues as far as he takes them (not pinned).

Military

Garrisons in the fortresses (no numbers in the sources).

Threats

The pope's demand that Peter be freed and Arborea restored
A Genoese expedition for Hugh

What the year holds

What happened next, if nothing in play changes it. Each event carries what it depends on and what would stop it.

Early 1200The pope refuses to confirm William's rule over Arborea and condemns the captivity of Peter and the pact with Hugh.Depends on: William still holding the captives. Stopped by: A settlement through Archbishop Ubaldo.
Beyond 1200: 30 October 1206A new pact with Hugh fixes Arborea's bounds; Cagliari keeps part of the north-eastern Marmilla.

Places of note

Castle of Arcuentu: Arborean mountain castle above Arbus; pledged to Genoa 1164, returned 1192
Castle of Marmilla: Border castle on the cone above Las Plassas; first document 1172 (pledge to Genoa), returned 1192

Where the sources disagree

Capture of Peter: about 1195 (DBI) or 1198 (English Wikipedia).

Evidence: That William held the main fortresses is stated by the DBI; the names of the castles are our inference from the castles documented before 1200.

On the map: Two castle discs stand for 'the main fortresses'; Oristano is shown as Arborea's town record.

Primary sources for Cagliari

Chronicles, registers, sagas and inscriptions written in or near 1200 that cover this entry. Each has its own page with editions, translations and where to read it.

Annals of Genoa, by Caffaro and his continuators, with Ogerio Pane for 1197 to 1219, Ogerio Pane and the other official annalists of Genoa (year by year under the commune's authority; the 1197 to 1219 section by Ogerio Pane). The official record of the commune. Read online
Annals of Pisa, by Bernardo Maragone, with continuation, Bernardo Maragone (1160s to 1175, continued to 1192). Pisa's official annals stop in 1175 and their continuation in 1192, so there is no Pisan narrative for 1200 itself. Read online
The register of San Pietro di Silki (11th to 13th centuries). A monastic register of lands, serfs, gifts and lawsuits in the giudicato of Torres (Logudoro), written in the vernacular.

Sources and studies

Last revised 4 November 2026. Published 4 November 2026. Suggest a correction on the OMNIA Discord.