This tragedy is founded on historical truth. A duke of Brittany in the year 1387 commanded the lord of Bavalan to assassinate the constable of Clisson: Bavalan the day after told the duke it was done: the duke becoming sensible of the horror of his crime and apprehensive of the fatal consequences of it abandoned himself to the most violent despair: Bavalan after giving him time to repent at length told him that he had loved him well enough to disobey his orders.