that he had never promised Charlemagne his allegiance. Meanwhile, the force sent by the Baghdad caliphate seems to have been stopped near Barcelona. After a month of siege at Zaragoza, Charlemagne decided to return to his kingdom. On his retreat, Charlemagne suffered an attack from the Basques in central Navarra. As a reprisal he attacked Pamplona, destroying it. However, on his retreat north his baggage train was ambushed by the Basques at the Battle of Roncevaux Pass on August 15, 778. Charlemagne's conflict with the Umayyad Emir of Cordova is one of the possible military conflicts which made him an ally of Harun al-Rashid, as they found a common enemy to unite against. For Charlemagne, the alliance may also have functioned as a counterweight against the Byzantine Empire, which was opposed to his role in Italy and his claim to the title of Roman Emperor. For Harun al-Rashid, there was an advantage in having a partner against his rivals in the Emirate of Cordova (Al-Andalus). Embassies After these campaigns, there were again numerous embassies between Charlemagne and the Abbasid caliph Harun al-Rashid from 797, apparently in view of a Carolingian-Abbasid alliance against Byzantium, or with a view to gaining an alliance against the Umayyads of Cordova. Three embassies were sent by Charlemagne to Harun al-Rashid's court and the latter sent at least two embassies to Charlemagne. The 797 embassy, the first one from Charlemagne, was composed of three men, Isaac the Jew (probably as interpreter), Lantfrid and Sigimud. Four years later in 801, an Abbasid embassy arrived in Pisa. They met with Charlemagne who was present in Italy at that time. In 799, Charlemagne sent another mission to the Patriarch of Jerusalem, with which the Patriarch of Jerusalem sent Charlemagne the keys to the Holy Sepulcher and the site of Calvary, as well as a Jerusalem Banner. In 802, a second embassy was sent by Charlemagne, which returned in 806. In 807, Rodbertus, Charlemagne's ambassador died as he returned from Persia. In turn, Abdallah, Harun al-Rashid's envoy reached Charlemagne in Aachen accompanied by two monks from Jerusalem, George and Felix, who represented of the Patriarch Thomas. The third and final embassy was sent by Charlemagne in 809, but it arrived after Harun al-Rashid had died. The embassy returned in 813 with messages of friendship, but little concrete results. Diplomatic gifts The embassies sent by Charlemagne possessed sundry royal red fabrics,