This coin was minted while Domitian was Caesar under his father Vespasian. Caesar by this time in the empire had become a political term used to identify heirs to the imperial throne. This coin was minted between 72 and 73 CE, soon after the final defeat of the Jews who had revolted in Judea. Domitian had been left in Rome during Vespasian's, and his brother, Titus's campaigns in Judaea and had therefore had taken no part in the war. Nevertheless, Domitian, being a Caesar, although not the one to succeed Vespasian, was allowed to ride in the triumphal parade, which celebrated the victory. It is this celebration that most likely is being depicted on the reverse of this coin. Andrew Carroll 2011.
Domitian was the last in the Flavian line and had little to do with the Jewish Wars. He minted these coins with the equestrian image, which was common rhetoric for a victorious general, in order to strengthen his connection with his militarily successful father and brother. BRS