Companion cavalry
Although the Companion cavalry is largely regarded as the first real shock cavalry of Antiquity, it seems that Alexander was very wary of using it against well-formed infantry, as attested by Arrian in his account of the battle against the Malli, an Indian tribe he faced after Hydaspes. There, Alexander did not dare assault the dense infantry formation with his cavalry, but rather waited for his infantry to arrive, while he and his cavalry harassed their flanks. It is a common mistake to portray the Companion cavalry as a force able to burst through compact infantry lines. Alexander usually launched the Companions at the enemy after a gap had opened up between their units or disorder had already disrupted their ranks. However, the ancient historian Arrian implies that the Companion cavalry were successful in an assault, along with heavy infantry, on the Greek mercenary hoplites serving Persia in the closing stages of the Battle of Granicus. Their success may have been largely due to the poor morale of the hoplites, who had just witnessed the rest of their army broken and put to flight.