Nithardus, whose account of the exchange of oaths at Strassburg is translated below, was an active participant in the events of the first half of the ninth century. He was born about 790, his mother being Charlemagne's daughter Bertha and his father the noted courtier and poet Angilbert. In the later years of Charlemagne's reign, and probably under Louis the Pious and Charles the Bald, he was in charge of the defense of the northwest coasts against the Northmen. He fought for Charles the Bald at Fontenay and was frequently employed in those troublous years between 840 and 843 in the fruitless negotiations among the rival sons of Louis. Neither the date nor the manner of his death is known. There are traditions that he was killed in 858 or 859 while fighting the Northmen; but other stories just as well founded tell us that he became disgusted with the turmoil of the world, retired to a monastery, and there died about 853. His history of the wars of the sons of Louis the Pious (covering the period 840-843) was undertaken at the request of Charles the Bald. The first three books were written in 842, the fourth in 843. Aside from a rather too favorable attitude toward Charles, the work is very trustworthy, and the claim is even made by some that among all of the historians of the Carolingian period, not even Einhard excepted, no one surpassed Nithardus in spirit, method, and insight. It may further be noted that Nithardus was the first historical writer of any importance in the Middle Ages who was not some sort of official in the Church. Source--Nithardus, _Historiarum Libri IV._ ["Four Books of Histories"], Bk. III., Chaps. 4-5. Text in _Monumenta Germaniae Historica, Scriptores_ (Pertz ed.), Vol. II., pp. 665-666. [Sidenote: Movements of the hostile parties in 841-842]