It is in 840/41 that we first hear of Musa ibn Musa himself. In response to attacks on the lands of his half-brother, Íñigo Arista, and the expulsion of kinsman Abd al-Jabbar al-Qasawi by the brothers Abd Allah and Amir ibn Kalayb, governors respectively of
Zaragoza and
Tudela, Musa and Íñigo rose in rebellion against emir
Abd ar-Rahman II. This led to a reprisal campaign under the leadership of the emir's son, Mutarrif, and general
Abd al-Wahid ibn Yazid Iskandarani. In 842, Musa was in charge of the vanguard of the emir's army marching against
Cerdanya, but believing himself mistreated by the commanding general, Musa again rebelled and along with his nephew,
García Íñiguez of Pamplona, defeated a
Cordoban army. Musa ibn Musa and Íñigo Íñiguez again joined forces to ambush and capture one of Abd ar-Rahman's commanders in 843, al-Harit, but the consequence was a massive military response from Córdoba, led by the
Emir in person, resulting in the defeat of the allies and the taking of slaves in the vicinity of
Pamplona. A second retaliatory expedition in 844 inflicted a further defeat, in which Fortún Íñiguez, the premier soldier of Pamplona, was killed and Musa and Íñigo barely escaped, while hundreds of the Pamplona nobility defected to the Cordoban side. Musa submitted and in November led his troops to
Seville, helping to defeat a large army of
Viking raiders who
had sacked the city. However, he again rebelled the next year. When
Muhammad, son of Abd ar-Rahman, took Tudela, Musa submitted, offered his sons as hostages and went to the emir's court. In 846 Musa again was forced to submit, this time to the emir's son Hisham, but Abd ar-Rahman was again forced to launch punitive campaigns against Musa in 847, and in 850 when Musa and Íñigo again joined in rebellion, Musa's son
Isma'il ibn Musa playing a critical role in the uprising. Throughout this time, Musa faced opposition from within his family. Ibn Hazm reports that his brother, Yunus ibn Musa, remained loyal to Córdoba, and joined with the sons of their uncle Zahir ibn Fortun to fight Musa ibn Musa for most of his life, about 30 years. ==Third King of Spain==