Conquest of the Green Shell astalakians
The city state of Oshamnus' first major conquest of a non-merfolk province was of the now defunct Greenshell Kingdom of astalakians. While the crab folk were called "Green Shells" they didn't have literal green shells. They did have a very rich quarries of virdilut so they were almost literally armed to the teeth in green colored armaments. The Green Shell astalakian had superior weapons and fortifications. The Oshamnus had greater mobility and more combat veterans. It was sort of an irresisitble force versus immovable object. The merfolk could not really breach most of the crab people's fortresses but the astalakians struggled to decisively defeat the fishtails in the open sea. There were lots of indeterminate skirmishes with mild losses. A bitter stalemate went on for years before a cunning mermaid general was able to out maneuver the bulk of the Green Shell army with a series of feints and planned retreats to pull most of the astalakians out of positions allowing a second army to stage a sneak attack and lay siege to a number of under manned astalakian fortresses housing a majority of the hatchlings of the Green Shell leaders. With their children as hostages, the astalakians sued for peace. The merfolk had won the war with relatively little actual blood shed. The Green Shells expected that they would have to yield some or all of their virdilut quarries. The Oshamnus merfolk instead let them keep all of their territory and made the Green Shell king into an an Oshamnus governor. The Green Shell astalakians were allowed to manage their own affairs as long as they periodically supplied virdilut weapons, tools, and building supplies to the city of Oshamnus.
The Green Shell astalakians resented being a conquered a state, but a lot of nurseries of Astalakian hatchlings were moved in or near the city of Oshamnus meaning any reprisals against the Oshamnus merfolk endangered their children. In the immediate aftermath of the end of the military campaign, most Green Shell resistance was targeted towards astalakians who were labeled as "fishtail collaborators".
The Oshmani did not brutally oppress the conquered Green Shell Astalakians. Overtime, both the merfolk and the Astalakians assimilated cultural practices of the other group and both groups prospered. Centuries ago, the Green Shell province resented their foreign conquerors, now most living in the Green Shell province are very patriotic and loyal supporters of the Imperial Stingray.
Historical SignificanceThe Oshamni Empire now have a large mutli-ethnic multi-racial empire all united under the banner of the Imperial Stingray. Centuries ago, Oshamnus was just a simple merfolk dominated city state that had absorbed a few neighboring merfolk provinces by sword or politiical marriage but they had very few non-merfolk subjects. At the time, it was not common practice for any monarch to rule over many different races. Merfolk ruled over heir own kind, astalakians ruled over their own kind, ojiongo etc. In the past, if different races fought they usually sought to wipe out or push out their enemies from desired territories. Such conflicts more often than not ended in a genocidal purge or a massive forced exodus of the defeated people, but only rarely did one race try to dominate another. This changed the miitary playbook. The Oshamni Empire usually opted to assimilate their neigbors rather than eradicate or displace them. As the tides of victory and prosperity came in for the Oshamni again and again as a result of this policy, other undersea powers gradually adopted this practice and multi-racial kingdoms and empires became the norm in Scaraqua rather than the exception.
Many Scaraquan historians view the conquest of the Green Shell Crabs as a major turning point, in a way the true birth of the Oshamani Empire. Once armed with astalkaian-crafted weapons the Oshamnus merfolk truly became a force to be reckoned with. This is when their annexation of new territory began to occur very quickly.