In 1256, he reunited Chartres with Blois on the death of his cousin Matilda of Amboise. He passed these lands on to Joan before his death.
John and his wife founded several religious institutions, including the Monastery of La Guiche.
In 1260 John granted the parish of Chouzy the right to organize a match of joule (a precursor of rugby) on Whitsun, a right that was practised for more than five centuries. It was an example for other parishes, who obtained similar privileges from their lords.
