[3] By the summer 1342, Peter together with the Raoul I of Brienne, Count of Eu, was given command of the covering force protecting France from attacks from the north while King Philip VI campaigned in Brittany.

In August 1343 he and the Dauphin of Viennois were the French ambassadors at a peace conference at Avignon, but the negotiations were fruitless, as Edward III of England declined to send any but the most junior members of the embassy.

Bourbon set up headquarters at Angoulême and begun an extensive recruitment campaign to raise a new army, command of which fell to the Duke of Normandy.

The Earl of Derby exploited the absence of a French commander in the field to lay siege to the important fortress-city of La Réole.

Bourbon and the Bishop of Beauvais raised a new army at Toulouse, in part financed by the Pope whose nephew had been captured by Derby the previous year, while John of Normandy brought with him a substantial number of nobles from the north including such dignitaries as the Eudes IV, Duke of Burgundy, Raoul II of Brienne, Count of Eu the Constable of France, both Marshals and the Master of Crossbowmen.

In January 1355, Peter was sent together with the Chancellor of France Pierre de la Forêt on a diplomatic mission to Avignon where they were to meet with an English embassy led by Henry of Lancaster and Richard FitzAlan, 10th Earl of Arundel.

The purpose of the mission was to formally ratify a peace treaty based on a draft drawn up at Guînes the previous year.

Peter was killed in the Battle of Poitiers 19 September 1356[5] and buried in the now-demolished church of the Couvent des Jacobins in Paris.