 Together and with Pisan support, the brothers invaded Cagliari in March 1164, reconquering the city, and then Arborea in April, where they holed up Barisone in his castle of Cabras.Though he was allied to Pisa through his mother and his allies in the war against Arborea, he was constrained to turn to Genoa later that year.In 1166, Barisone and Peter travelled to Pisa to explain the bloody reprisals of the citizens against the Pisans in Ottana.