Powerless Adherbal accepted and peace was made. Shortly after, in 113 BC, Jugurtha again declared war on his brother, and defeated him, forcing him to retreat into Cirta, Adherbal's capital. Adherbal held out for some months, aided by a large number of Romans and Italians who had settled in Africa for commercial purposes. From inside his siege lines, Adherbal appealed again to Rome, and the Senate dispatched a message to Jugurtha to desist. The latter ignored the demand, and the Senate sent a second commission, this time headed by Marcus Scaurus, a respected member of the aristocracy, to threaten the Numidian king into submission. The king, pretending to be open to discussion, protracted negotiations with Scaurus long enough for Cirta to run out of provisions and hope of relief. When Scaurus left without having forced Jugurtha to a commitment, Adherbal surrendered. Jugurtha promptly had him executed, along with the Romans who had joined in the defence of Cirta. But the deaths of Roman citizens caused an immediate furore among the commoners at home, and the Senate, threatened by the popular tribune Gaius Memmius, finally declared war on Jugurtha in 111 BC. In 111 BC the consul Lucius Calpurnius Bestia commanded a Roman army against Jugurtha, but he allowed himself to be bribed. The following year the consul Spurius Postumius Albinus succeeded the command against the Numidian king, but he let himself be bribed too. Spurius's brother, Aulus Postumius Albinus, allowed Jugurtha to lure him into the desolate wilds of the Sahara, where the cunning Numidian king, who had reportedly bribed Roman officers to facilitate his attack, was able to catch the Romans at a disadvantage. Half the Roman army were killed, and the survivors were forced to pass under the yoke in a disgraceful symbolism of surrender. The Roman Senate, however, when it heard of this capitulation, refused to honour the conditions and continued the war. After Postumius' defeat, the Senate finally shook itself from its lethargy, appointing as commander in Africa the plebeian noble Quintus Caecilius Metellus, who had a reputation for integrity and courage. Metellus proved the soundness of his judgement by selecting as officers for the campaign men of ability rather than of rank, men like Gaius Marius and Publius Rutilius Rufus.