 Charles typically tried to exploit the situation by making agreements with both sides that would enlarge his territory while leaving Navarre itself relatively untouched.Officially he was ally of Peter of Castile, but at the end of 1365 he concluded a secret agreement with Peter IV of Aragon to allow the marauding army led by Bertrand du Guesclin and Hugh Calveley invade Castile through southern Navarre in order to depose Pedro I and supplant him with his half-brother Henry of Trastámara.He then reneged on his agreements to both sides and attempted to hold the Navarrese borders intact, but was unable to do so and instead paid the invaders a large sum to keep their plundering to a minimum.