Charles probably may have taken Narbonne had he been willing to commit his army and full resources for an indefinite siege, but he was not willing to do so. He had accomplished his primary goals by destroying the Arab armies. The Arabs were temporarily contained to the city of Narbonne, though a second expedition was needed later that year to regain control of Provence after Arab forces returned. According to Paul the Deacon's Historia Langobardorum the Arabs retreated when they learned that Martel had formed an alliance with the Lombards. Martel's remaining years - he had only four to live - were spent setting up and strengthening the administrative structure that became the Carolingian Empire, and the feudal state that would persist through the Dark Ages. His son would return in 759 and finish his father's work by taking Narbonne and driving the Emirate of Cordova back over the Pyrenees.