 Philip VI ordered his son to abandon the siege and march north; after several delays John did, arriving in Picardy two weeks after Philip's army had been decisively beaten at the Battle of Crécy with very heavy losses.The areas facing Derby were left effectively defenceless, and he sent local Gascon forces to besiege the few major strongholds in the region still held by the French.Taking a force of approximately 2,000 Derby set out from La Réole on a grand "chevauchée", a great mounted raid.