The Battle of Selinus, which took place early in 409 BC, is the opening battle of the so-called Second Sicilian War. The ten-day-long siege and battle was fought in Sicily between the Carthaginian forces under Hannibal Mago (a king of Carthage of the Magonid family, not the famous Hannibal of the Barcid family) and the Dorian Greeks of Selinus. The city of Selinus had defeated the Elymian city of Segesta in 415, an event that led to the Athenian invasion of Sicily in 415 and ended in the defeat of Athenian forces in 413. When Selinus again worsted Segesta in 411, Carthage, responding to the appeal of Segesta, had besieged and sacked Selinus after the Carthaginian offer of negotiations had been refused by the Greeks. This was the first step towards Hannibal's campaign to avenge the Carthaginian defeat at the first battle of Himera in 480. The city of Selinus was later rebuilt, but never regained her former status.
Background
The island of Sicily contained the Elymians, Sikans, and the Siculi living in respective communities before the Phoenicians had started their colonisation of Sicily after 800 BC. The Phoenicians had initially planted trading posts all over the coast of Sicily, but never penetrated far inland and ultimately withdrew without resistance to the western half of the island (concentrating in the cities of Motya, Panormus, and Soluntum) with the arrival of the Greek colonists after 750. The Ionian Greeks took the lead in colonising Sicily among Greeks when they planted Naxos in 735, and spread north and west along the island coast until the city of Himera was founded in around 648, bordering the Phoenician territory of Soluntum. The Dorian Greeks founded Syracuse in 734 and spread south then west along the coastline until Selinus was founded around 654, bordering the Phoenician territory of Motya. While the Ionian Greeks on the whole had friendly relations with the native Sicilians and the Phoenicians, the Dorian Greeks were comparably more aggressive, pushing inland at the expense of the natives to expand the Greek domain. Conflicts among the Greeks colonies and between the natives and Greeks erupted, but these were mostly localised affairs without any decisive results or intervention from non-Sicilian powers. The Phoenicians and Carthaginians traded with everyone in Sicily and on the whole all the island colonies prospered. This prosperity caused some of the Greek cities to start to expand their territories again, ultimately leading to the events known as the Sicilian Wars.
Carthaginian hegemony
The Phoenicians in Sicily had not resisted the initial Greek expansion by force of arms, but this state of affairs changed when the Greeks began to encroach on their territory in Western Sicily. Phoenicians had aided the Elymians against the Dorian Greeks of Selinus in 580, when a Greek colonization attempt of the area around future Lilybaeum (which lies across the Phoenician colony of Motya) was defeated by their joint effort. Nothing is known of the role of Carthage in this episode, and it is possible that the Sicilian Phoenicians were not a part of the Punic hegemony at that time. The Carthaginian king Malchus is said to have "conquered all Sicily" and sent booty captured to Tyre sometime after this event. This probably implies that Carthage had incorporated the Phoenician colonies of Motya, Panormus, and Solus into the Punic hegemony led by Carthage, which had begun to resist Greek encroachment of the Western Mediterranean after 600 BC. The growth of Selinus and Himera during the period Malchus was active in Sicily indicates that Carthaginians were not in conflict with the Sicilian Greeks at that time. However, Carthage countered the expedition of Spartan Dorieus in 510 and the Greeks were defeated near Eryx, a clear indication that Carthage now held sway over the Phoenician interests in Sicily. A war followed this event, which eventually led to Carthage destroying the city of Heraclea Minoa. The year this event took place is not known, but Carthage did not intervene in Sicily again until 480 after Heraclea had been destroyed. Carthage granted the Sicilian Phoenicians local autonomy, keeping control of their foreign policy, extracting some sort of tribute in exchange for military aid. The Elymians, dominated by Segesta, were given allied status, protecting them from further hostility of Selinus, which had also allied herself with Carthage because of the threat presented by the rise of Akragas.
Greek tyrants
Two Greeks from Gela, Cleander and Gelo, had been involved in the war that eventually destroyed Heraclea Minoa. An appeal for aid to avenge the death of Dorieus was ignored by mainland Greece, even by Leonidas of Sparta, the brother of Dorieus and who later would win immortal fame at a narrow pass called the Gates of Fire near Thermopylae in 480. While Carthage was engaged in Sardinia, the Greek colonies in Sicily had fallen under the rule of tyrants. Some of these tyrants, notably those ruling Gela, Akragas, and Rhegium, sought to expand their dominion at the expense of native Sicilians and other Greek cities during 505 -480 BC, with the Dorian city of Gela being the most successful. Tyrants like Cleander and Hippocrates successfully took over Sicel and Ionian Greek territory, and by 490, Zankle, Leontini, Catana, and Naxos had fallen under Gelan control. Syracuse had managed to survive the attempts of Hippocrates with help from Corinth, but Gelo, the successor of Hippocrates, captured Syracuse and made the city his capital. Akragas expanded her territory against the Sikans and Sicels, and under Theron, allied with Gelo to forestall any future conflicts between the neighboring powers. The Ionian Greeks, having lost Naxos and Catana to Gelan aggression, responded by creating an alliance between tyrants of Himera and Rhegion. Anaxilas, tyrant of Rhegion, who had managed to detach Zankle from the clutches of Syracuse by 485 BC, married the daughter of Terillus, tyrant of Himera. Both Himera and Rhegion also made treaties with Carthage. Terillus went further, becoming guest-friend of Hamicar Mago, "king" of Carthage.
Thus three powers were delicately balanced in Sicily by 483. Carthage kept the peace between Elymians and Selinus, while the Ionian Greeks in the north (led by Himera and Rhegion) faced the Dorians Greeks from the South, led by Syracuse and Akragas. This situation changed when Theron, with support from citizens of Himera, deposed Terillus and took over that city in 483 BC. Carthage intervened at the instigation of Anaxilus, and the Sicilian Greeks under the tyrants Gelo and Theron crushed the Punic expedition of 480 in the 1st battle of Himera. The Carthaginian domain in Western Sicily was untouched by this defeat. Carthage had refrained from intervening in Sicilian affairs for 70 years while expanding her hegemony in Africa, Sardinia and Spain.
This defeat of an external power brought prosperity, but not peace, for Sicilians, Greeks, and non-Greeks alike. The political landscape in Sicily during those years changed as some of the Greek tyrants were replaced by democracy and oligarchy, the influence of Syracuse shrank in Sicily and infighting between the Greek cities flared up. Athens had sent fleets to Sicily in 427, 425 and 424 to intervene in these conflicts, which ultimately caused Hermocrates of Syracuse to request all Sicilian Greek cities to remain at peace at the congress of Gela in 424. Peace between Greeks and the natives of Sicily was not part of this agreement. Ironically, the defeated Carthaginians and their allies, the Elymians seem to have enjoyed comparably more peaceful existence after the battle of Himera until 415.
Selinus versus Segesta
Greek Selinus and Elymian Segesta share a long history of trade and conflict. The cities were trading partners and had a close enough relationship to have passed laws allowing inter-marriage between citizens. There had been conflicts as well; The Phoenicians had aided the Elymians to beat back the Greek invasions of 580 and 510 BC of Lilybaeum and Eryx. It is unknown what role Segesta played in the war where Carthage destroyed Minoa. Segesta was neutral during the first battle of Himera (ironically Selinus had sided Carthage). The period following Himera was one of prosperity for both cities. Around 454 BC, a conflict involving Motya, Segesta, Selinus and Akragas took place, details are confusing except that Carthage was not involved, Selinus won a victory and the Elymians had appealed for aid from Athens without any known results. After a peace lasting almost 3 decades, Segestan power seem to have weakened and Selinus opened hostilities in 416 BC.
Athenenian expedition
The Greeks of Selinus crossed the upper reaches of the River Mazaros and occupied some disputed lands on the border of Segestan domain and started to raid Segestan territory. Segesta requested the Greeks to stop, and when this was not heeded, they managed to recapture the lands, but the Greeks defeated them in a later battle. Segesta then requested Akragas and Syracuse to intervene in vain, in fact Syracuse joined Selinus and sent a fleet to blockade the Elymian coast. In desperation Segesta sent an embassy to Carthage, but the Carthaginians refused any aid. Segesta had allied with Athens in 426 BC when they had intervened in Sicily for the first time and an embassy was sent to Athens begging aid. The resultant Athenian invasion of Sicily during 415-413 BC was destroyed by a combined effort of Sicilian cities including Selinus and Syracuse. As an ally of Athens, the position of Segesta had become precarious.
Renewed Selinute aggression
After the Athenian defeat, Selinus sought to expand her domain again. Her geographic position meant an expansion had to be against either Motya to the West or Akragas to the east or against Segesta to the north. Conflict with Motya meant taking on Carthage, while Akragas was the wealthiest city in Sicily and a relatively stronger opponent compared to Segesta. Furthermore, Segesta was allied to an enemy power and conquering the Elymians would have given Selinus control of an area rivaling that of Syracuse in size and direct land access to the Tyrrhenian Sea – and direct trade route with the Etruscan and Massaliot markets.
Selinus resumed hostilities in 410, again reoccupying the disputed lands across the River Mazaros. Segesta, fearing that any resistance would bring Syracuse into the fray against them, remained passive, but the Greeks continued to raid Segestan domain. Segesta now sent an embassy to Carthage begging for protection.
Carthaginian response
Carthage, during the 70 years following the battle of Himera, had expanded her domain in Africa, explored new trade routes on the Atlantic coasts of Africa and Europe and had pacified Sardinia under the leadership of the Magonid dynasty, but had not intervened in Sicilian affairs – and Sicilian Greeks had also refrained from provoking her. By changing trade patterns and consolidating markets Carthage had by 430 amassed a huge hoard of gold and silver. The Greeks were aware of the growing power of Carthage, which is why Syracuse had contemplated requesting her aid against the Athenian invasion, while the Athenians actually asked Carthage for aid during the invasion. Carthage had denied aid to both, and also declined to help Segesta in 416. The situation was different in 411, when the Segastans renewed their plea.
Reason for intervention
Firstly, Segesta decided to submit to Carthage and become a dependent ally. This probably meant that Segesta would retain internal and commercial autonomy, but surrender control of foreign policy, pay for any Punic garrison housed in Elymian territory and perhaps pay tribute in return for Carthaginian protection. Secondly, one of the Suffets of Carthage was Hannibal Mago, a member of the Magonid dynasty – and no lover of Greeks. From the Carthaginian prospective, probably three factors stood out: A victory over Selinus would mean a strong power in Western Sicily capable of supporting Punic interests, the submission of Segesta would enlarge the Carthaginian domain, but at the same time any intervention risks a war with the mighty Syracuse. The Carthaginian Senate debated the matter at length, and the influence of Hannibal finally secured a verdict for accepting Segestan submission to the Punic hegemony and lending aid to Segesta. Hannibal was authorized to aid Segesta by any means necessary.