He invaded the giudicato and forced Peter to flee to the court of his elder brother Barisone II of Logudoro at Porto Torres. In March 1164, the Barisone and Peter, united with the Pisans of the island, retook the city of Cagliari and then invaded Arborea in April. The judge of Arborea took refuge in the castle of Cabras.
The invader entered the giudicato and pressured Peter to seek safety at his elder brother Barisone II of Logudoro's court in Porto Torres. In March 1164, Barisone and Peter, along with Pisans from the island, recaptured Cagliari and then invaded Arborea in April. The Arborean judge took refuge in Cabras Castle.