|Bertrada of Laon|
There appears to have been bad blood between the brothers, but little agreement as to the cause. Consider, however, that the two were very young when their father—and both boys, to ensure the dynasty's legitimacy—was anointed by Pope Stephen II. They had both grown up believing it was their destiny to rule. Also, they had never known a divided kingdom. Their father had united the two parts, and then extended the borders into Aquitaine. In 768, after the kingdom of the Franks had been unified for 20 years, to have it made smaller again by dividing it might have tried the patience of the most peaceable of brothers. Perhaps a mother's influence might have softened the sibling rivalry, except that this mother had a favorite.
Bertrada of Laon married Pepin in 740—and here is another potential reason for the brothers' hostility. "Married" might not be considered a flexible term in this case. (Remember that it would take the church another 500 years to codify marriage a little more strictly.) Pepin was apparently married earlier to a Leutberga, of whom little is known—still married, technically. He put his first wife aside in order to choose Bertrada. Charles was born in 742 from this second union. Pepin and Bertrada's marriage was not confirmed by the church until years later. After the marriage was considered legitimate, Carloman was born. Carloman may have considered himself the legitimate heir, even though Charles was the elder.
Bertrada was an educated woman and spoke Latin. When Pepin went to Narbonne to fight Saracens, she accompanied him. This desire to be involved in politics meant she wasn't going to sit idly by while her sons ruled their respective parts of the kingdom. We'll see a little more of that tomorrow.