An integral part of the peace negotiations was the marriage contract between Louis and Maria Theresa, which he used to justify the 1666 to 1667 War of Devolution, and formed the basis of French claims over the next 50 years. The marriage was more significant than intended, since it was agreed shortly after Philip's second wife, Mariana of Austria, gave birth to a second son, both of whom died young. Philip died in 1665, leaving his four year old son Charles as king, once described as "always on the verge of death, but repeatedly baffling Christendom by continuing to live."