At an unidentified location in southern Hispania, the forces of Roderic, King of the Visigoths, and the invading Arab-Berber armies of Tariq ibn Ziyad have finally met.
Ibn Ziyad was supported by Julian (Ilyan in Arabic), the lord of Ceuta, and may have been helped cross the straits of Gibraltar. Although many have versions of the story, ibn Ziyad may have landed in Cartagena where he made it as headquarters while other chroniclers point it to Cadiz.
During this time, Roderic was busy fending off the Basques before he turned his attention to meet the invading Muslim armies while its been said that the Arab attacks also coincided by a Byzantine attack in southern Hispania that was later repulsed Theudimer, the count of Baetica.
Prior to the actual “battle,” there were inconclusive pitched skirmishes near the lake La Janda and the plain stretching from the Rio Barbate to the Rio Guadalete. It was said that ibn Ziyad was marching towards Cordoba after defeating a Gothic army along the way. The armies of Roderic and ibn Ziyad met in Shedunya (probably Medina Sidonia) while other historians placed the encounter at Jerez de la Frontera.
The armies that met in battle were not reliably described in the surviving records. The Muslim army was predominantly Berber cavalry under Arab leadership. Roderic’s troops gathered during his return to the south after confronting the Basques. A small number of about 25 elite clans, their warrior followings, the king and his, and the forces that could be raised from the royal fisc constituted the troops upon which Roderic could draw.
It was believed that the defeat of the Visigothic army followed on the flight of the king’s opponents like Sisibert, who had only accompanied the host “in rivalry”, “deceitfully”, and “out of ambition to rule” says the Mozarabic chronicler. Chroniclers and historians recounted how the Muslim army engaged in a series of violent hit and run attacks while the Visigothic lines maneuvered en masse. A cavalry wing under Sisibert, who secretly pledged to rebel against Roderic, had stood aside to give the enemy an opening. In a devastating attack, ibn Ziyad’s mujaffafa cavalry (made up as much as a third of the total force), which was armored in coats of light mail and marked by a turban over a metal cap, exploited the opening and charged into the Visigothic infantry. It was soon followed by the infantry.
The Visigothic army was routed and the king slain in the final hours of battle. The resulting bloody engagement resulted in extremely high Visigothic losses and a quarter of the invading army lost their lives.
Roderic’s enemies from within may have intended to abandon him on the field for the Muslims to defeat and kill him. It may be attributed to his own undoing and his treachery towards his subjects and the killing of his rivals. The sons of the late king Wittiza may have conspired to kill Roderic. In fact, Wittiza’s brother Oppa was found in Toledo, possibly as king-elect, by Musa ibn Nusayr when he took the city. Even the Gothic nobleman Theudimer made an alliance with the invaders to preserve his own rule of his territory. Within a decade all of the peninsula save the tiny Kingdom of Asturias and the mountain-dwelling Basques was under Muslim dominion and they had advanced beyond the Pyrenees as well.
The later Arabic historians universally credit their religion for the victory in this statement:
Remember that I place myself in the front of this glorious charge which I exhort you to make. At the moment when the two armies meet hand to hand, you will see me, never doubt it, seeking out this Roderick, tyrant of his people, challenging him to combat, if God is willing. If I perish after this, I will have had at least the satisfaction of delivering you, and you will easily find among you an experienced hero, to whom you can confidently give the task of directing you. But should I fall before I reach to Roderick, redouble your ardor, force yourselves to the attack and achieve the conquest of this country, in depriving him of life. With him dead, his soldiers will no longer defy you.
It is also widely believed that Jews that were progressively disenfranchised under the rule of the Catholic kings and the bishops have provided fighters to augment the Moorish forces. One of these prominent Jewish fighters who served with the Muslim invaders was Kawlah al-Yahudi, who distinguished himself in the battle at the head of a mixed contingent of Jews and Berbers, In the aftermath of victory, the Jews reputedly took several cities and were even commissioned to garrison Seville, Córdoba, and Toledo itself.