[1] Otto took part in the reconquista (Christian reconquest) of the Muslim port city of Almería by a league of Genoa and the Kingdom of Castile–León with their respective allies in 1147.
When the Siege of Almería began in August 1147, the Castilian king, Alfonso VII the Emperor, was away campaigning against the Muslims in the region of Jaén.
[2] The Genoese delegated Otto to go to his camp and remind him of his duty to his allies: They sent Oto de Bonovillano as a legate to the Emperor who was at Baeza.
On 11 November the republic leased out its third for a period of thirty years to Otto, who had played such a prominent rôle in the negotiations and the conquest.
[5] After the Genoese fleet sailed, taking with it the plunder to pay off the republic's war debt, Otto was left to guard the city with a thousand men, "which he did", in the words of Cafarus.