Battle of Tunes
The Battle of Tunes fought in 255 B.C. was part of the First Punic War fought between Rome and Carthage. After Regulus won the Battle of Adys for Rome and gave harsh peace terms that instead led Carthage to continue the war, Carthage called upon the Spartan mercenary Xanthippus to fight for them. Xanthippus, with a revitalized Carthaginian army faced off against Regulus in Africa, each with about 20,000 men. Xanthippus' made good use of his cavalry, elephants, and a phalanx of Greek mercenaries to defeat the Romans, capturing about half the Roman army and Regulus himself. The remainder of the Romans, perhaps 5,000 men, entrenched themselves in an inaccessible position and were later rescued by a Roman fleet.
Encyclopedia of Military History, Dupuy & Dupuy, 1979