born 535
died November? 575, Vitry, near Arras
Frankish king of the Merovingian dynasty .
On the death of his father, Chlotar I , he became king of Austrasia, and he gained further territory on the death of his brother Charibert I (с 567). He repelled attacks by the Brunhild , the daughter of the Visigothic king. Brunhild's sister had married Sigebert's brother Chilperic I and was murdered by him. To avenge his sister-in-law's murder, Sigebert waged civil war against Chilperic, defeating him and taking most of his land. Acclaimed king by his brother's subjects, he was immediately killed by assassins in the service of Fredegund , Chilperic's second wife.