Complex sentence: It has been said that Louis married, in secret in 1464, Catherine, daughter of Arnold, Duke of Gelderland; these claims date only from the seventeenth century and are now believed to be false.
Split into simpler sentences: It has been said that Louis married, in secret in 1464, Catherine, daughter of Arnold, Duke of Gelderland. These claims date only from the seventeenth century and are now believed to be false.