It was part of a decade of intense activity by Louis against the Umayyad Emirate of Córdoba in the region of the lower Ebro.
[7] The Muslim Arabic chroniclers Ibn ʿIdhārī and al-Maqqarī note two Carolingian attacks on Tortosa in the period AH 192–193 (807–809).
[15] The Emperor Charles sent his own vassus and missus, Ingobert, to begin the siege, while Adhemar and Bera again launched raids across the Ebro.
They nonetheless managed to sack an Umayyad camp and defeated an army sent by ʿAbdūn, the wālī (governor) of Tortosa, before going home with substantial loot.
[12] The main accounts of the siege operations and outcome, in the Vita Hludovici and the Annales regni Francorum, do not exactly match: On arriving [at Tortosa, Louis] battered and wore down the city[19] with rams, mangonels, covered sheds, and other torments,[20] so that its citizens abandoned hope, and seeing that Mars had turned against them and that they were beaten, they handed over the keys of the city, which Louis on his return sent to his father with great satisfaction.
These events, carried out in such a way, struck great anxiety in the Saracens and Moors, for they feared a similar fate might be in store for each city.
[21] In the west the Lord King Louis entered Spain with his army and besieged the city of Tortosa on the River Ebro.
[22] The "covered sheds" in the Vita's description of Louis siege works refers to mobile shelters used to protect soldiers from projectiles.
[2] Although some historians read the Vita as saying that Louis succeeded in breaching the walls,[2] most agree that he simply accepted a formal act of submission and retired.
The caliph's son and heir, the future ʿAbd al-Raḥmān II, along with the commander of the Upper March, ʿAmrūs ibn Yūsuf, is said to have led a relief force that rescued the city.