He was consequently attacked by William II of Cagliari and Marianus II of Torres. They desired to maintain a condominium in Arborea, but internal fighting allowed Peter to solidify his authority with little opposition.
He was subsequently challenged by William II of Cagliari and Marianus II of Torres, who sought to preserve their claim to Arborea through a shared rule. Meanwhile, internal power struggles enabled Peter to strengthen his position with minimal opposition.