The battle of the Helorus River (c.493 BC) saw Hippocrates, tyrant of Gela, defeat the army of Syracuse, but he was unable to capitalise on his victory by capturing the city.
Very few details of the battle have survived, and even the date is something of a guess, as the sources for Hippocrates' career don't put events in any clear order.
The River Helorus (modern Tellaro) is one of the largest in south-east Sicily, and flows into the sea south of Syracuse. In its lower reaches it is a slow flowing almost stagnant river but further upstream it is more of a mountain stream. The battle is mentioned in passing in one of Pindar's victory odes, (the 9th Nemean Ode, addressed to Chromios son of Agesidamos, a winner at the Pythian Games at Sikyon. Chromios fought at the battle, probably on Hippocrates' side). Pindar places the battle at a ford called the 'Fountain of Ares', in an area where the river had steep cliffs as its banks. This suggests that the battle took place somewhere inland.
Other than that we know nothing about the course of the battle other than that a number of prisoners of war were captured by Hippocrates.
After the battle Hippocrates moved towards Syracuse and camped in the precincts of the temple of Olympian Zeus. Diodorus has very little on Hippocrates, but he does include a story about his time at the temple. On his arrival Hippocrates found the priests of Zeus attempting to take away the gold dedications in the temple and the gold robe on the statue of Zeus. Hippocrates expelled the priests and ordered them to go back to the city. He then left the temple untouched in an attempt to improve his reputation.
Syracuse was saved by the intervention of her mother city of Corinth and fellow Corinthian colony of Corcyra. The two cities intervened, although Herodotus doesn't tell us how (either diplomatically or militarily). Hippocrates agreed to leave Syracuse alone and return the prisoners captured at the Helorus River. In return he was given Camarina, a colony of Syracuse on the River Hipparis, east of Gela.