[235] Chron. Namnet. in _Rer. Gall. Scriptt._, vol. vii. pp. 217, 218; Chronn. Rainald. Andeg., S. Serg., Vindoc., a. 843 (Marchegay, _Eglises d’Anjou_, pp. 5, 129–132, 158). [236] Ann. Bertin. a. 851 (_Rer. Gall. Scriptt._, vol. vii. p. 68) mention the cession of Nantes, etc. That the Mayenne was made the boundary of the two kingdoms appears from a charter of the Breton king Herispoë, dated August 23, 852; “Erispoë princeps Britanniæ provinciæ et usque ad Medanum fluvium.... Dominante Erispoë ... in totam Britanniam et usque ad Medanum fluvium.” Lobineau, _Hist. de Bretagne_, vol. ii. p. 55. [237] Ann. Bertin. a. 853 (_Rer. Gall. Scriptt._, vol. vii. p. 70). In a breathing-space which followed upon this last attack, Charles received from Æthelwulf of Wessex a personal visit and an overture of mutual alliance against the common foe. The scheme was shattered by a political revolution in Wessex which followed Æthelwulf’s return; and meanwhile a new danger to the Karolingian power arose in the threatening attitude of Robert the Brave, a warrior of obscure birth who was now count of the Angevin march. Under pretext, as it seems, of securing their aid against the northmen, Robert leagued himself with the foes of the monarchy beyond his two frontier rivers, and made a triple alliance with the revolted Bretons and the king’s rebel nephew, Pepin of Aquitaine.[238] Charles, more and more hard pressed every year by domestic and political difficulties, and haunted by the perpetual horror of the pirate ships always in the background, felt that this second wavering lord of the marchland must be won back at any cost. Two years later, therefore, the count of the Angevin march was invested with a vast duchy comprising the whole territory between Seine and Loire as far as the sea and the Breton border; and with this grant the special work of keeping out both Bretons and northmen was distinctly laid upon his shoulders.[239] [238] Ann. Bertin. a. 859 (_Rer. Gall. Scriptt._ vol. vii. p. 75). [239] Regino a. 861 (Pertz, _Mon. Germ. Hist._, vol. i. p. 571). Ann. Mettens. a. 861 (_Rer. Gall. Scriptt._, vol. vii. p. 190).