He was educated at the imperial court and became abbot of St Riquier in commendam, never taking the vows. Little else is known about his life, but he appears to have served his cousin, Charles the Bald, on peaceful errands and also on the field of battle. He fought for Charles at Fontenoy in June 841, and died as the result of wounds received whilst fighting for him against the Northmen near Angoulême. The date of his death was probably June 14, 844. In the 11th century his body, with the fatal wound still visible, was found in the grave of his father, Angilbert.
Nithard's historical work consists of four books on the history of the Carolingian empire under the turbulent sons of the emperor Louis I, especially during the troubled period between 840 and 843. The Historiae or De dissensionibus filiorum Ludovici pii (On the Dissensions of the Sons of Louis the Pious) is valuable for the light which it throws upon the causes which led to the disintegration of the Carolingian empire. Although rough in style, partisan in character and sometimes incorrect in detail, the books are the work of a man who had an intimate knowledge of the events which he relates, who possessed a clear and virile mind, and who above all was not a recluse but a man of action. They are dedicated to Charles the Bald, at whose request they were written.
See also: Oath of Strasbourg