The Bosporan Civil War or the First Bosporan Civil War was a dynastic dispute from 310 to 309 BC between the sons of Paerisades I. These sons were Satyros II, who inherited the kingdom as he was the eldest, Eumelos, who was a claimant to the throne, and Prytanis, who engaged in battle later on.
Cause
Paerisades, one of the sons of Leukon I, died in 310 BC after having ruled 38 years; his eldest son, Satyros II, inherited the kingdom from his father. Eumelos was not pleased with this, and fled Panticapaeum and was given refuge by the ruler of the Sarmatian tribe of Siraces, Aripharnes. After gathering a large army and making an alliance with the neighboring barbarians, Eumelos became a claimant to the Bosporan throne. Upon hearing this, Satyrus immediately left Panticapaeum under Prytanis and sallied out against his brother, cornering him with his baggage wagons in the banks of the river Thatis with Aripharnes.
Size of Bosporan army
The Scythians partook in this war because their rivals, the Siraceni, were trying to gain influence in the Bosporus and possibly take some of the land of the Scythians. It is very likely that the mercenaries employed by Satyrus were recruited from Bosporan cities. For some unknown reason, Satyros did not use the citizen Bosporan army, probably due to there being shifting allegiances, and instead left them to protect the cities.
Size of Siracen army
It is important to note that the Scythians and Sarmatians were most likely competing for influence and territory.
Satyrus mobilized his army into battle formations, placing himself in the center in a phalanx formation. He had stationed his Greek mercenaries and Thracian peltasts to his right, and his Scythian allies to his left. Satyrus rounded his best troops and charged at Aripharnes, who was opposite him, in the center of the enemy line. The two sides sustained many losses, but Satyrus was able to rout Aripharnes and he gave chase to kill the fleeing enemy but stopped when he received news that his brother Eumelos was winning at the right wing, and that his mercenaries had begun to flee. He turned around and aided his own troops and was able to route his brother's entire army.
After the routing of their army, Aripharnes and Eumelos fled to Siracena, the Siracen capital and fortified city. Satyrus gave chase to his brother, but made the observations that the city was situated on the river Thatis, it was surrounded by thick forests and long cliffs and only had two artificial entry ways: one through the main gate, and another through the palace of Aripharnes, both of which were heavily defended. Knowing that it would be suicide to attack the main city, Satyrus decided to let his army plunder the nearby villages and attained from this many prisoners. Satyrus then ordered some of his men to start cutting some trees to make a pathway from their camp, to the main gate. While this was carried out, Aripharnes believed that the only way of safety was victory and stationed archers on both sides of his city. Satyrus's men, while cutting the trees, started to take fire from Siracen wall defenders, who were throwing spears and arrows at them. After four days of cutting, on the fourth day, his army made it to the Siracen walls, but had sustained many losses getting there. Meniscus, the mercenary Greek captain, fought with bravery and boldness when he entered the city, but had to retreat when he was overcome by enemy forces. Upon seeing this, Satyrus rushed to his aid and fought bravely, but was struck in his right shoulder by a spear and was carried back to his tent. Satyrus died that night. Meniscus, seeing no point in carrying out the siege, ended it and took Satyrus's body to Gargaza to be sent off to Panticapaeum.
Later battles
Prytanis, who held a great funeral for his elder brother, hurried to Gargaza and took both the royal power and control of the army. Eumelos, perhaps testing his fortunes, sent envoys to Prytanis to discuss partition of the kingdom between themselves but to this, Prytanis declined. After that, Prytanis left a garrison in Gargaza and hurried back to Panticapaeum to seize the royalties that he was entitled to. Gargaza While Prytanis was away, Eumelos and perhaps Aripharnes took the chance and attacked Gargaza, capturing it in the process. He also plundered various towns neighboring Gargaza and its land. Battle of Lake Maeotis Prytanis sallied out against his brother, but was defeated by Eumelos. He surrendered his throne to Eumelos, in exchange for his life. Upon re-entering Panticapaeum, the capital city of the rulers of the Bosporus, he attempted to regain his kingdom, but was overpowered and fled to a place called "The Gardens" which may mean Kepoi, which was a place gifted to Gylon of Cerameis, the grandfather of Demosthenes by Satyrus I for giving them Nymphaeum over a century earlier in the Bosporan wars of expansion, Prytanis and Eumelos's great-grandfather. Here he was killed by Eumelos.
Aftermath
Eumelos became ruler of the Bosporan Kingdom after solidifying his reign by killing the families and friends of his brothers, and re-took various colonies that had been lost in the years before his rule such as Tanais. He successfully cleared the Black Sea of pirates and gained much fame throughout the Bosporus. He expanded his realm so much, that it could rival that of Lysimachus.