When Tarik, lieutenant of Musa, came with a force of seven thousand Berbers to battle for the Prophet and to conquer Spain, the Gothic King, Roderic, hastily collected an army of defence and advanced towards Xeres. Theodomir, Governor of Andalusia, had learned that the invaders were marching from Algeciras, where they landed on the 30th of April 711. The Berbers had many horsemen, well-equipped and valiant, while Roderic possessed only a small number of mounted men.
It was not until 19th July that the decisive and memorable battle was fought. The Gothic King met his foes on the banks of the Guadalete (Wad-el-leded) 'the river of delight.' It is said that the combat lasted for seven days. The Goths, though enervated, had not wholly lost their prowess, and they strove desperately with the fierce host of Tarik. So bravely fought the defenders that the Moors grew disheartened; but their leader, sword in hand, and calling upon Allah, told his troops that they had no vessels with which to escape from the country. The Berbers must win or perish. Spurring his steed, Tarik dashed into the Gothic ranks, cleaving a way as he rode, and inspiring his followers to a supreme effort. Roderic also rallied his soldiers to a last stand. His army numbered more than that of the Berber general, but the men were ill-trained, and no match for the desperate enemies who had battled in many campaigns.
Some Spanish historians assert that the sons of Witiza, the King dethroned by Roderic and sentenced to death, aided by other traitors, deserted their companies and joined the Berbers. It has also been recorded that Count Julian, whose daughter was dishonoured by Roderic, had allied himself with the foe in Africa. These stories have not, however, been accepted by later chroniclers.
The battle was to the Moors. Roderic was either killed on the field by Tarik himself, or taken prisoner and released to spend the rest of his days in a monastery. One account states that Tarik slew his opponent, and sent the head to Musa, who had it conveyed to the Court at Damascus. The beaten Goths retreated rapidly before the advancing army. Some followed Theodomir into Murcia, others went to the Asturian mountains. The band of the Andalusian Governor was pursued by the enemy and routed; and Theodomir was compelled to surrender and to confess fealty to the Khalif. Upon this condition the Governor was allowed to possess Murcia and parts of Valencia and Granada, his territory being known as Tadmir.
Seville was soon in a state of siege. Envious of the good fortune of his lieutenant, Musa came to Andalusia with eighteen thousand Arabs of valour. He was assisted in command by his sons Abdelola and Meruan. His eldest son, Abdelasis, remained in authority in Africa. The Sevillians made a valiant defence of their beautiful city; but after several weeks of siege Musa led his army through the gates. From that hour, until its capture by Fernando III., the Andalusian capital was in the hands of the Moors. Carmona and neighbouring towns were also seized by Musa.
After the subjection of Seville, the Arab general started upon a campaign. It appears that Musa had not left an efficient force within the city walls, for the inhabitants rose and attempted to expel their victors. Hearing of the trouble, Musa sent his son Abdelasis into Spain to quell the revolt in Seville. Abdelasis used suasion first; but the natives were in arms and ardent to regain the city. They prepared for a second siege. With much slaughter, the son of Musa put down the rebellion of the newly-conquered citizens, and proceeded through the south of Spain, winning battles everywhere. Musa was so gratified by his son's successes that he appointed him ruler of the annexed territory.
Abdelasis had a reputation for humane conduct towards the vanquished people. He fell in love with Egilona, widow of the unfortunate Roderic, and made her first a member of his harem and afterwards his wife. That he respected her is shown by the fact that her counsel was always sought in affairs of government.
The Berber King of Seville was to learn that the throne is not the most peaceful resting-place after war's alarms. Scandal was set abroad that Abdelasis was scheming to become sole ruler of the Berber dominion, and this report reached the ears of Suleyman, brother and heir of the Khalif. There is no doubt that Suleyman resented the favour shown to Musa and his sons, while he feared that Abdelasis might one day contest with him for sovereignty. Seized by this fear, the heir to the crown gave secret orders for the killing of the three sons of the great commander, Musa.
One day, while Abdelasis was taking part in the devotions within the Mosque of Seville, hired murderers crept up to him and stabbed him to death. The two brothers of Abdelasis shared the like fate. The head of the King was sent to the Khalif at Damascus, who caused it to be shown to Musa. Then the brave general, gazing in anger upon his sovereign, cried aloud: 'Cursed be he who has destroyed a better man than himself!' The distracted Musa fell sick through grief, and soon died.
There is another account of the death of Musa. His jealousy of Tarik, who conducted the first successful campaign in the Peninsula, led the general to treat his inferior officer with indignity. The friends of Tarik at Damascus, in the Court of the Khalif, breathed vengeance upon Musa, and prevailed upon the monarch to punish his commander-in-chief. A party of arrest seized Musa in his camp, and brought him before the Khalif, who commanded that he should be degraded and publicly beaten. The disgrace broke Musa's heart and caused his death.