Complex sentence: An agreement was indeed reached; it stated that Edward would voluntarily relinquish his continental lands to Philip as a sign of submission in his capacity as Duke of Aquitaine and in return Philip would forgive him and restore his land after a grace period.
Split into simpler sentences: An agreement was indeed reached; it stated that Edward would voluntarily relinquish his continental lands to Philip as a sign of submission in his capacity as the duke of Aquitaine. In return, Philip would forgive Edward and restore his land after a grace period.