Rhesus or Rhêsos (Greek: Ῥῆσος) was a Thracian king who fought on the side of Trojans in Iliad, Book X, where Diomedes and Odysseus stole his team of fine horses during a night raid on the Trojan camp. Homer gives his father as Eioneus— a name otherwise given to the father of Dia, whom Ixion threw into the firepit rather than pay him her bride price. The name may be connected to the historic Eion in western Thrace, at the mouth of the Strymon, and the port of the later Amphipolis. The event portrayed in the Iliad also provides the action of the play Rhesus, transmitted among the plays of Euripides. Scholia to the Iliad episode and the Rhesus agree against Homer's version in giving Rhesus a more heroic stature, incompatible with Homer's version.-- Wikipedia
Rhesus died without engaging in battle.