The Arevaci assembled at the town of Numantia which had strong natural defences, and chose Ambo and Leuco as their leaders. Three days later Nobilitor encamped four kilometres from the town. He was joined by 300 cavalry and ten elephants sent by Masinissa, the king of Numidia, a Roman ally in Africa. Before the ensuing battle Nobilitor placed the elephants at the rear so that they would not be seen and then divided the army into two. During the battle he brought them into view. This frightened the enemy, who had never seen these animals. They fled inside the town. Nobilitor attacked the city walls and there was a fierce battle. Then an elephant was hit by a large falling stone and made a loud noise which frightened the other elephants. They went on the rampage, trampling over the Romans, who took to disorderly flight. The Numantines made a sortie and killed 4,000 Romans and three elephants. Nobilitor then attacked the town of Axinium which stored the enemy supplies, but did not achieve anything. He lost many men and returned to his camp at night. He sent his cavalry commander to pursue an alliance with a neighbouring tribe and ask for cavalry assistance. He was given some horsemen, but an ambush was prepared against him when he was on his way back. The allied horsemen fled and the Roman commander and many of his troops were killed. These Roman disasters encouraged the town of Ocilis (Medinaceli, also in the modern province of Soria) to defect to the Celtiberians. The Roman provisions were kept in this town. Nobilitor withdrew to his winter camp and suffered food shortages. Because of this, as well as heavy snowstorms and frost, many of his men died.