In the second half of his reign Charles very frequently took the field in person, but was not so constantly at the head of his armies as during the period 773-85. [Sidenote: Charles makes his sons kings.] He had now three growing sons, whom he intrusted with the charge of three important sections of his realm, and he looked to them to guard each that portion of the frontier of the Frankish empire which bordered on his own sub-kingdom. Charles, the eldest of the three, ruled in western Neustria (Anjou, Maine, Touraine); Pippin, the second, in Lombardy; Lewis, the youngest, in Aquitaine. Charles would thus be specially concerned with the unruly Bretons of Armorica, who twice made unsuccessful risings in his father’s reign (786 and 799). Lewis was in charge of the Saracen frontier along the Pyrenees. Pippin had to keep watch over the duke of Benevento, as well as to turn his attention to the Avars on the north-east of Italy. But the three princes were not strictly confined each to his own sphere. Charles was occasionally sent against the Saxons; Lewis conducted at least one campaign in southern Italy; Pippin more than once took charge of an attack on the Slavs of Bohemia. Whenever, in short, the great king could not march in person against a rebel or a foreign enemy, he would send one of his sons to take his place. He did not allow them to become completely localised and engrossed with the affairs of their respective governments, but often kept them with him at Aachen for many months at a time. In reviewing the later conquests of Charles the Great it will be most convenient to follow the geographical order from north to south, rather than the chronological order of each campaign, for his arms were engaged in so many quarters at once that an attempt to tell his doings in a purely annalistic form leads to dire confusion.