Edward was crowned at age fourteen after his father was deposed by his mother, Isabella of France, and her lover Roger Mortimer. At age seventeen he led a successful coup d'état against Mortimer, the de facto ruler of the country, and began his personal reign. After a successful campaign in Scotland he declared himself rightful heir to the French throne in 1337. This started what became known as the Hundred Years' War. Following some initial setbacks, this first phase of the war went exceptionally well for England; victories at Crécy and Poitiers led to the highly favourable Treaty of Brétigny, in which England made territorial gains, and Edward renounced his claim to the French throne. This phase would become known as the Edwardian War. Edward's later years were marked by international failure and domestic strife, largely as a result of his inactivity and poor health.