Pepin tried to ensure a peaceful transfer of power after his death by dividing the kingdom beforehand between his two sons, Carloman and Charles. The restless region of Aquitaine he left to the two princes jointly, in the hope that a common interest would unite them in subjugating future revolts there.
At first Pepin’s plan seemed to work. For six months after his death, Charles and Carloman each ruled their own territories in peace. However, when the inevitable trouble did break out in Aquitaine, Carloman left the problem entirely in Charles’s hands. The twenty-six year old Charles defeated the rebels, but the concept of a two-fold rule had been irreparably damaged. Only the intervention of Bertha, the Queen Mother, prevented open conflict between the two brothers.
In Italy, Desiderius, the new king of the Lombards, sensing division in the Carolingian court, put new pressures on the Papal States. Bertha thought an alliance with Desiderius would remove the threat of constant conflict between the two kingdoms, and she travelled to the Lombard court to arrange a marriage between Charles and Desiderius’ daughter, Desiderata. The match arranged, Charles dutifully repudiated his first wife and married the Lombard princess.
Within a year, however, Charles disowned his new wife and returned her to her father. Desiderius inevitably sought to redress this insult to his name through force of arms. He was to prove no match, however, for the young Frankish king.