The Battle of Chrysas was a battle fought in 392 BC in the course of the Sicilian Wars, between the Carthaginian army under Mago and a Greek army under Dionysius I, tyrant of Syracuse, who was aided by Agyris, tyrant of the Sicel city of Agyrium. Mago had been defeated by Dionysius at Abacaenum in 393, which had not damaged the Carthaginian position in Sicily. Reinforced by Carthage in 392, Mago moved to attack the Sicles allied with Syracuse in central Sicily. After the Carthaginians reached and encamped near the river Chrysas, the Sicels harassed the Carthaginian supply lines causing a supply shortage, while the Greek soldiers rebelled and deserted Dionysius when he refused to fight a pitched battle. Both Mago and Dionysius agreed to a peace treaty, which allowed the Carthaginians to formally occupy the area west of the River Halycus, while Dionysius was given lordship over the Sicel lands. The peace would last until 383, when Dionysius attacked the Carthaginians again.
Background
Dionysius attacked the Phoenician city of Motya in 398 BC, igniting the first of four wars he was to lead against Carthage between 398-368. After the sack of Motya, Dionysius retired to Syracuse, while Himilco of Carthage arrived in Sicily with 50,000 men along with 400 triremes and 600 transports to continue the war. in 397.
Himilco first stormed Motya, where the mostly Sicel garrison under Biton was easily overcome, then lifted the siege of Segesta, and Dionysius retired to Syracuse instead of offering battle in Western Sicily against a superior army. Himilco returned to Panormus, garrisoned the Carthaginian territories, and then sailed to Lipara and collected 30 talents of silver as tribute. The Carthaginian force next sailed for Messana and easily captured and sacked the city. Himilco founded the city of Tauromenium and populated it with allied Sicels, then moved south towards Catana. Dionysius moved his forces to Catana also but, due to the rash tactics of his brother Leptines, the Greek fleet was heavily defeated at the naval battle of Catana. Himilco next besieged Syracuse itself in the autumn of 397. After the Carthaginian forces were devastated by a plague, Dionysius managed to decimate the Punic fleet and shut up the army survivors in their camp. Himilco, after bribing Dionysius, fled to Africa with Carthaginian citizens, while Dionysius enslaved the abandoned Carthaginian soldiers.
Sicily during 396-392 BC
The Sicilian Greek cities which had become tributary to Carthage after 405 had all revolted in 398, and along with the Sicels and the Sikans had joined Dionysius in his attack against Motya. After the defeat at Catana the Sicilian Greek soldiers had returned to their respective homes when Dionysius decided to withstand a siege in Syracuse against their wishes. The Sicels had also turned against Dionysius and had sent soldiers to help Himilco during the Carthaginian siege of Syracuse in 397 BC.
Carthaginian problems
The return of Himilco after abandoning his troops to the mercy of Dionysius did not sit well with either the Carthaginian citizenry or their African subjects. Himilco publicly took full responsibility for the debacle, dressed in rags visited all the temples of the city pleading for deliverance and finally committed suicide. The divine was not mollified as a plague swept through Africa weakening Carthage further, and to top things off, the Libyans, angered by the desertion of their kinsmen in Sicily, gathered an army numbering 70,000 men and besieged Carthage itself.
Mago, the victor of Catana, (and possibly a member of the Magonid family) took command. The standing Punic army was in Sicily and recruiting a new one would have been time-consuming and probably very costly (Himilco's abandonment would have made mercenaries wary), so he rallied Carthaginian citizens to man the walls while the Punic navy kept the city supplied, as the Libyans had no ships to counter the Carthaginian fleet. Mago then used bribes and other means to quell the rebels.
Mago in Sicily
After securing the safety of Carthage, Mago moved to Sicily, where the Punic city of Solus had been sacked by Dionysius sometime in 396 BC. Carthage was unwilling or unable to provide Mago with additional forces, and he had to make do with the Punic garrison left by Himilco and whatever forces he could gather in Sicily. The Carthaginians caught a break when Dionysius chose not to invade the Punic territories in Western Sicily immediately lifting the siege of Syracuse. The Elymians had stayed loyal to Carthage since the start of the war, while the Sicilian Greeks and Sikans were not threatening and most of the Sicels were not hostile when Mago arrived in Sicily.