Hippocrates, Tyrant of Gela (fl.498-491 BC) created a short-lived empire in eastern Sicily and was one of the first Sicilian Tyrants known to have been a major military leader.
Hippocrates had a mixed army. We know that he had a bodyguard of spearmen and a cavalry force, as his successor Gelon was first a spearman of the guard and then commander of the cavalry. Hippocrates also commanded a number of Sicel mercenaries, the native inhabitants of eastern Sicily.
Gela became a tyranny in 505 BC when Hippocrates' brother Cleander seized power. In 498 BC, after seven years in power, Cleander was murdered by Sabyllos, an inhabitant of Gela. Hippocrates replaced him as tyrant. When he came to the throne Gela only held a small area of land, surrounding the city which was located on the southern coast of Sicily.
According to Herodotus Hippocrates captured Callipolis, Naxus, Zancle and Leontini, in that order. Gala is on the south coast of Sicily. Naxus is two thirds of the way up the east coast and Zancle (Messene) is near the northern end of the east coast. Leontini is further south, inland from a point about a third of the way up the coast, and this has led some to assume that Herodotus's order is wrong. The location of Callipolis is unknown but it was a colony of Naxus and so might also have been located in the north-east of the island. This might suggest that two separate wars are included in Herodotus's list - the first a campaign in the north-east in which Callipolis, Naxus and Zancle were taken, and second a campaign in the south east in which Leontini fell.
His possession of Zancle was not untroubled. After the battle of Lade (494 BC) some inhabitants of the island of Samos decided to leave their home, which was now dominated by the Persians, and found a new colony in the west. Zancle was ruled for Hippocrates by Scythes, a native of Cos. He invited the Samians to come to Sicily and settle in a new city he was planning to found, on the north coast. The Samians agreed to this, but on the way they stopped in at Rhegium, a Greek city on the Italian side of the straits of Messina. Anaxilas, tyrant of Rhegium, convinced them to seize Zancle instead of settling in the new city. At the time Zancle was undefended, as Scythes was away to the west establishing his new colony, and so the Samians were able to seize the place.
When Scythes discovered what had happened he called for help from Hippocrates. Hippocrates arrived with his army, but instead of restoring Scythes he arrested him, and then came to an arrangement with the Samians. They abandoned their alliance with Anaxilas, and in return were allowed to keep Zancle. The unlucky former inhabitants were sold into slavery. Hippocrates gave the three hundred most important citizens to the Samians to be executed, but the Samians spared their lives. Zancle remained part of Hippocrates' empire, although it was lost after his death.
Hippocrates' also made an unsuccessful attempt to capture Syracuse. He defeated the Syracusan Army at the battle of the Helorus River, and then tok up a position at the Temple of Olympian Zeus, near Syracuse. The city was saved by the intervention of her mother city Corinth and the sister colony of Corcyra. Hippocrates agreed to leave the city alone and return the prisoners taken at the battle, in return for the colony of Camarina, located east of Gela.
Hippocrates also fought against the Sicels, the native inhabitants of eastern Sicily. He won a number of victories against them, capturing unnamed cities. He also captured the otherwise unknown Sicel city of Ergetium, the source of some of his best mercenaries. The motive behind this move isn't entirely clear. The story is reported by Polyaen. Hippocrates posted the mercenaries from Ergetium close to the sea, with the rest of his army between them and their home. He then sent his cavalry to capture the empty city before turning on and massacring his mercenaries. This stratagem gave him possession of the town, but lost him some of his best troops.
Hippocrates was killed during an attack on the Sicel city of Hybla in 491 BC (there were at least five cities of that name on the island, all named after a local god). He was briefly succeeded by his sons Eucleides and Cleander, but the citizens of Gela rose against them in an attempt to overthrown the tyranny. They were defeated by Gelon, the commander of Hippocrates' cavalry. He then removed Eucleides and Cleander and became tyrant of Gela himself.