Gilles was born in 1404 at Machécoul, in the area on the border of Brittany and Poitou. He was an intelligent child, learning fluent Latin. In 1420 he found himself at the court of the Dauphin, the then uncrowned king of France. He was present there in 1429 when Joan of Arc arrived at the prince's court and proposed a plan for him to regain control of his throne from England. Gilles was by then a commander of some note in the prince's army, and his exploits against the English promised to make him almost as famous a hero as Joan. However, Gilles became fascinated with alchemy, and became convinced that the only way to succeed at that pseudoscience was to sell his soul to the Devil. A magician offered to put these two parties in contact. Gilles was persuaded that he would have to sacrifice a child to Satan in order to carry out his alchemical plans.
Local children began to disappear, and their disappearance was noticed. The remains of many of these children were found in his castles of Machécoul and Champtogne, where they were discovered in 1440 after Gilles quarreled with a person to whom he had sold another of his holdings. Gilles soon confessed to, and was convicted of heresy, sodomy, and witchcraft, and for these crimes he was swiftly put to death.
Gilles de Rais is the factual basis of the legendary character of \Bluebeard.