Ares’ name is often used in ways that make it clear that war is his realm, just as the sea is the realm of Poseidon, the underworld the realm of Hades, and the sky the realm of Zeus. In the Iliad, several characters refer to war as ‘the turmoil of Ares’. Nestor refers to a great clash of armies as a ‘deed of Ares’. The works of war are the works of Ares (Hom. Il. 11.732–36). The poet refers to war as ‘the strife of Ares’ (Hom. Il. 5.861; 14.149). It is at the hands of Ares that battles are endured (Hom. Il. 3.126–28), and it is by Ares that the combatants are slain: Nestor speaks of the many long-haired Achaians whose blood keen Ares has spilled around the river Skamander (Hom. Il. 7.328–30), while Priam tells both his household and Achilles that Ares has slain his many fine sons (Hom. Il. 24.253–62, 498).27 When the spears are flying, Ares guides their paths. The poet tells us how Ares causes spears to fall short from Meriones and Automedon (Hom. Il. 16.610–13, 17.525–29), just as he allows the spear to embed itself in the chest of Alkathous, robbing it of its momentum only once the man has been mortally wounded (Hom. Il. 13.443–44). In similar fashion, the sixth century poet Anakreon, as quoted in the Palatine Anthology, describes the battle-dead as being slain by Ares (Anth. Pal. 7.226 = Anac. fr.100D Diehl), as do the seventh-century Spartan poet Tyrtaios (Stob. Flor. 4.10. 6 = Tyrtaios fr.12 West) and a pair of Archaic inscribed epitaphs. To Anakreon, those who survive a battle do so because they have been spared by Ares (Anth. Pal. 7.160 = Anac. fr.100D Diehl).
Ares was unique amongst all the gods of the ancient Aegean in being a god whose name was used as a metonym for war. While divine warriors, patrons of warriors, protectors in battle, and bringers of destruction could be found throughout the Near East, only Ares was identified directly with war. The Classical Attic tragedians inherited the idea that Ares was both synonymous with war as its anthropomorphic personification and also its divine ruler, responsible for all deaths in battle and for the survival of all those who walked away. In this, Ares filled a distinct niche, more specific than Zeus and Fate, who ruled over all walks of life, and less partisan than the many warrior-protectors who stalked each battlefield. Stories about and cults for Ares therefore enabled the Greeks to engage with the idea of war as an independent force with a distinctive character. - Alexander T. Millington, Worshipping Violence, in Brill's Companion to Greek Land Warfare Beyond the Phalanx