Liber Historiae Francorum
The "Liber Historiae Francorum" seems to imply that Chlothar died in 719. It is more likely that he died in 718 between 24 February, the date of his last known act, and 18 May, when Wissembourg Abbey, which was loyal to Charles Martel and dated its charters by the reign of Chlothar IV, switched to dating them by Chilperic II. Charles's pursuit of Chilperic, which culminated in a negotiated settlement with Odo for the king's return, was probably required by the sudden death of Chlothar IV. It has even been suggested that the suddenness of his death is suspicious, indicating perhaps that Charles had him removed—as soon as he no longer need him—in favour of the more legitimate Chilperic. No primary sources casts any suspicion, however.