Before the outbreak of the Rostran-Ovinex war, the Ovinex Island Tribes had become increasingly antagonistic towards Rostran sailors who strayed too close to the Ovinex-held islands in Rostral C. Though the Rostrans and Ovinex were not at technological parity, with the Rostrans being significantly more advanced in terms of metallurgy and social organization, the Ovinex had numbers and aggression on their side. Ovinex raiders would regularly attempt to capture Rostran sailors, putting the slaves to work tending the fields, animals, and salt harvesting operations which functioned as the basis of the Ovinex's primitive economy. The Ovinex did this in part because, as descendants of herd animals, Ovinex society viewed slave-taking as a way to artificially increase the size, influence, and genetic diversity of one's tribe (or 'flock' as the term has been variously translated) while asserting dominance in the face of other males who might seek to claim control over the tribe. Furthermore, the Ovinex erroneously believed that the Rostrans shared this outlook, meaning that such activities would simply be accepted if the Rostrans weren't strong enough to resist.
Over time, Ovinex raiders became more bold, attacking coastal settlements to acquire additional slaves. Around this time, Rostrans who had lost loved ones at sea began to suspect that the reason no wreckage or bodies were ever found was because the Ovinex were actually eating any captives who could not find use as slaves - a supposition which had some basis in truth, as Ram Rex, the particularly vicious elements of Native Ovinex society, would often bite off parts of opponents who were too close to kick or headbutt effectively. When a group of Ovinex fishermen ran aground on the island of Exivaun (a core Rostran settlement), the Rostran populace took the incident as a sign that the Ovinex would eventually be able to reach every unfortified settlement - with dire consequences. As a result, the Rostran elders decided that an organized military response to the threat of Ovinex encroachment was necessary.
Ovinex raider crews operated somewhat independently, though the leaders of these crews could declare a 'moot' to arrange temporary alliances or trade slaves based on the needs of the tribes from which they hailed. Though only some Ovinex tribes would raid, the collectivist, herd-like psychology of the Ovinex meant that any tribe which harbored raiders did so by the consensus of the entire tribe, and adjacent tribes would not oppose the raiders for fear that they would turn to depose any males who opposed them.
For the Rostrans, the shared issue of Ovinex raiders forced the various tribes to co-police their territorial waters with militia forces. From the prelude to war, the necessity of this cooperation caused previously disparate Rostran tribes to interact more often with one another, with this military cooperation eventually leading to the formation of the Rostran Archipelago Confederacy and the formation of the first pan-Rostran fleet to deal with the raider menace. Exivaun became the meeting place for the new federal organization and the home port for Rostran naval operations.
The litoral waters of Rostral C were the primary battlegrounds of the Rostran-Ovinex war, though amphibious assaults against island targets also occurred (especially towards the conclusion of the war).
Ovinex warships at this time were large catamarans with 8-12 crew and were primarily oar-driven to maintain the stealth of a low profile in the water, though sails were occasionally used for long-range missions. Tandem catamarans were used as outriders. Ovinex raider vessels attacked in large swarms, often striking from the cover of darkness, fog, or coastal mangroves to further conceal their movements. Raider crews wore woolen padded armor and carried ba'amba
, obsidian-tipped spears, and bows, with all points and edges saturated in salt to increase the pain caused in a potential captive. Ovinex excelled at boarding actions, encroaching on a vessel from multiple directions and using their superior physical strength to best opponents in close quarters; this advantage disappeared in narrow waterways, a fact which Rostran captains often exploited to gain a tactical advantage.
Rostran warships at the time were swift sloops larger than those of their Ovinex counterparts (16-24 crew), with four-man catamarans operating in secondary roles. The Rostran fleets were smaller and more centralized and, therefore, had difficulty dealing with large raider swarms despite having superior firepower and speed on the water. Rostran crews enjoyed an advantage in ranged combat, being armed with crossbows, ballistae, black powder fireworks, and (rarely) primitive firearms. Rostran sailors rarely wore armor, preferring to remain unencumbered should swimming become necessary, though officers occasionally wore armor made of wicker or wooden slats over thick cloth. The comparative physical weakness of Rostran crews was offset by steel-bladed knives and spears which could pierce Ovinex body armor, though the Ovinex were stronger and could scale a vessel's hull and rigging with frightening speed. Unlike their Ovinex counterparts, the Rostran naval forces were largely uninterested in taking their opponents alive.
Over time, the numerical advantage of the Ovinex slave-takers was diminished by the superior technology (including early firearms) of their Rostran opposition. By the fifth year of the campaign, Rostran militiamen had taken and fortified the outlying islands of Ovinex territory to such a degree that the bronze-age Ovinex could not hope to retake them. Rostran sorties into the surrounding significantly curtailed Ovinex seafood production and communication between the Ovinex tribes involved with slave-taking.
In Native Ovinex culture, the ability to physically defeat an opposing male is usually enough to assert dominance over that male's previous holdings, a cultural hold-over from when the Ovinex were wild sheep who would compete over mates. Besieged, hungry, and desperate, the Ovinex slave-taking tribes began make displays of murdered Rostran slaves as such a means of psychological warfare. The Ovinex, however, did not understand at that time that Rostrans did not share their ovine psychological traits; to the Rostrans, presenting a slain ally is a sign that an opponent cannot be trusted as a prisoner and must be terminated. As a result of this action, the tribes which demonstrated this tendency were systematically destroyed to the last adult by Rostran expeditionary forces.
Witnessing these battles from afar, the less agressive Ovinex tribes quickly sent a few female tribe members (a sign of submission to a superior male in Ovinex culture) as envoys to the Rostran admiral overseeing the campaign. The Rostran fleet admiral, cognizant that the Ovinex he had captured previously appeared to have a different outlook and more primitive cognitive set than his own people, felt that there would be no honor in exterminating the Ovinex completely. Perhaps, he reasoned, the Ovinex had been acting more out of ignorance than inherent evil, as the submitting tribes seemed not to understand that fighting and enslaving Rostrans couldn't 'bring the herds together' as fighting other Ovinex could. He set about creating non-aggression pacts with each tribe who submitted and established permanent naval ports on the islands he had captured thus far to enforce the new geopolitical order.
In the aftermath of the Rostran-Ovinex War, the Ovinex were made to understand that they could no longer attack the Rostrans directly without deadly repercussions. Captured Ovinex and the female envoys sent to the Rostran fleet admiral were not allowed to leave Rostran territory, serving as hostages to prevent the naturally collectivist Ovinex from attacking for fear that their compatriots would suffer repercussions. These prisoners were, however, allowed to freely participate in Rostran society provided that they followed the laws of the then-nascent Rostran Archipelago Confederacy. This served as a way to teach Ovinex how to interact with Rostrans in a more peaceable manner, leading eventually to economic ties between the Rostran Archipelago Confederacy and the Ovinex Island Tribes that served to further dis-incentivize open warfare.
The descendants of the Ovinex hostages became known as Civil Ovinex, having adopted some High Rostran cultural values over the course of generations of acculturation. Civil Ovinex now account for around half of the total Ovinex population, living alongside Rostrans as honorary 'members of the flock.'