Dimachae
Introduction '''Dimachae''' (, from δίς ''dis'', "two, double, twice" and μάχη ''mache'' "fight") were Macedonian horse-soldiers, who also fought on foot when occasion required. Their armour was heavier than that of the ordinary horse-soldier, and lighter than that of the regular heavy-armed foot-soldier. A servant accompanied each soldier in order to take care of his horse when he alighted to fight on foot. This species of troops is said to have been first introduced by Alexander the Great.Seems that there was also a similar unit among the Celtiberians.
References This article incorporates text from a publication now in the public domain: Smith, William, ed. (1870). Dictionary of Greek and Roman Antiquities. London: John Murray.