Charles III of Alençon was the eldest son of Charles II of Alençon

Charles II of Alençon

Charles II of Alençon, called the Magnanimous was the second son of Charles of Valois and his first wife Margaret, and brother of Philip VI, King of France...

 and Maria de la Cerda.

He succeeded his father as Count of Alençon in 1346, but resigned the county to his brother Peter II of Alençon

Peter II of Alençon

Peter II of Alençon, called the Noble , was the son of Charles II of Alençon and Maria de la Cerda. He was Count of Alençon 1361–1404 and Count of Perche 1377–1404....

 in 1361 to take up an ecclesiastical career.

On 13 July 1365, he was made Archbishop of Lyon. As archbishop, he firmly resisted royal encroachment on his rights as Primate of France.