 Peter led a contingent of Genevans in an invasion of the Kingdom of Naples in 1382.The invasion was led by his lord, Amadeus VI, Count of Savoy, and by Louis I, Duke of Anjou, the adopted son and heir of the imprisoned Queen Joan I of Naples, all supporters of his brother's claim to the papal throne.He was present at the deathbed of Amadeus at Castropignano on 1 March 1383.