Either the power and popularity, or the rich marriage-portion, which Sigbert acquired with Brunhilde, induced his brother, Chilperic, to ask the hand of her sister, the Princess Galsunta of Spain. It was granted to him on condition that he would put away all his wives and live with her alone. He accepted the condition, and was married to Galsunta. One of the women sent away was Fredegunde, who soon found means to recover her former influence over Chilperic's mind. It was not long before Galsunta was found dead in her bed, and within a week Fredegunde, the murderess, became queen in her stead. Brunhilde called upon Sigbert to revenge her sister's death, and then began that terrible history of crime and hatred, which was celebrated, centuries afterwards, in the famous _Nibelungenlied_, or Lay of the Nibelungs. In the year 575, Sigbert gained a complete victory over Chilperic, and was lifted upon a shield by the warriors of the latter, who hailed him as their king. In that instant he was stabbed in the back, and died upon the field of his triumph. Chilperic resumed his sway, and soon took Brunhilde prisoner, while her young son, Childebert, escaped to Germany. But his own son, Merwig, espoused Brunhilde's cause, secretly released her from prison, and then married her. A war next arose between father and son, in which the former was successful. He cut off Merwig's long hair, and shut him up in a monastery; but, for some unexplained reason, he allowed Brunhilde to go free. In the meantime Fredegunde had borne three sons, who all died soon after their birth. She accused her own step-son of having caused their deaths by witchcraft, and he and his mother, one of Chilperic's former wives, were put to death. Both Chilperic and his brother Guntram, who reigned at Orleans, were without male heirs. At this juncture, the German chiefs and nobles demanded to have Childebert, the young son of Sigbert and Brunhilde, who had taken refuge among them, recognized as the heir to the Frankish throne. Chilperic consented, on condition that Childebert, with such forces as he could command, would march with him against Guntram, who had despoiled him of a great deal of his territory. The treaty was made, in spite of the opposition of Brunhilde, whose sister's murder was not yet avenged, and the civil wars were renewed. Both sides gained or lost alternately, without any decided result, until the assassination of Chilperic, by an unknown hand, in 584. A few months before his death, Fredegunde had borne him another son, Clotar, who lived, and was at once presented by his mother as Childebert's rival to the throne. [Sidenote: 597.]