Arguably the events that set this story into motion, it is a bit of a cyclic thing for the high elves to attempt incursions onto the mainland as their cousins that live on the continent are rarely cooperative due to their pure bred cousins hating them almost as much as humans. As a result they must build up the forces (those Dumauri they still control on their small continent) and their equipment (elves can still make small batches of old tech but it takes quite a while) to invade. Cartheen refuse to 'down turn' the technology their warriors use, though improved versions of human weapons are typically issued to their dumauri warriors.
The motivation for this particular invasion may be the complex that will be at the center of the story, the human pre-war installation (Abyssal Mountain Complex?) that was studying interdimensional travel via a techno-magical gate. It was sealed by a direct hit from some nuclear scale weapon during the apocalypse and the lower areas of the facility where left intact, perhaps even with those within escaping to some other place through the device itself.
The Cartheen goal may have been to secure the device and the complex for their own use or they may not even be aware of it only knowing it as a possible depository or cache of ancient tech that the human power in the region is unaware of. But overall they land on the western coast of the continent in force and push east. Ultimately driven off by the combined efforts of the local powers and eventual intervention by the Rothian Realm (after Sarsella takes power, the previous emperor not interested in stopping a foothold). The consequences of this invasion however are dire for the Barony; its army and navy gutted, its infrastructure in the region severely damaged, and its population brutally reduced. This would leave it vulnerable to events later on.
Current idea is that old man Sarsella was a general in the Rothian Imperial Army at the time and the current leadership was at the tail end of its decline via both incompetence, in fighting, and perhaps even heavy high elf magical influence. Their fall will probably have been by a coup led or in the very least allowed by the noble/lord class of the Rothian Empire and various military types who could see the coming fall and wish to stop it, in this case perhaps under the control of Sarsella himself. However rather than stabilizing the situation our lords and nobles have the entire ruling family killed rather than the defective ruler (Romanov'd) and begin to bicker and threaten one another over who will control what. Seeing the writing on the wall for the future stability of the empire under these fools as well as the recent invasion of the Lebian Barony in the south Sarsella makes a decision. With his loyal units he has the nobles responsible for planning the coup killed and seizes the throne for himself, the first time in nearly two centuries someone of his standing has sat upon it. Due to his popularity in the armed forces the noble classes are unable to unseat him through force and his immediate moves to bring about some reform removes the possibility of a general uprising from the general population.
Due to a rise in the trade tariffs on Galliporian shipping through the narrows into the Golden Sea by the Trade State and a steady decline in the current leadership's popularity a military operation to seize the coastal strip of land down to the Islin'net Gulf is launched. Gallipor enjoys significant success in the first few days of their operation via both surprise and a well plan logistical base but a naval and air attack along with poor unit training eventually ground the invasion to a halt. While unable to commit a general attack of significance into the larger nation Bakharel is able to launch various hit and run raids on border installations and eventually contribute to the withdraw of Galliporian forces from their territory.
Gallipor has been undergoing a foundation deep shakeup with the rise of the Junta and the throwing off of the old Thar system and now the Junta begins to look west toward the still exhausted kingdom of Lebia as a means to attain what they had sought from Bakharel. Soon a series of small border clashes occur between the skeleton of what the barony has on its border and the newly reformed and equipped Galliporian army.
Roughly four Galliporian divisions and one additional division made up of various mercenary and 'donated' (Rothian) units are assembled outside the gate complex with the required logistics to support them in place. The invasion itself begins with roughly two battalion sized 'foot' units being sent through followed by another battalion's worth of engineers who immediately set to work in preparing the site to handle the larger numbers that will be flowing through on the following day.
The location the device portal'd to is remote, though on the previous expedition scouts had found numerous dirt tracks that led down to more developed roads until they'd sighted the nearby settlement and fallen back to report. The site had changed little from the previous arrival, a wide open mountain meadow surrounded by tall pines which where promptly fell'd to make way for construction even as the perimeter is pushed out.
By the end of the day roughly three regiments worth of personnel are camped around the gate with more arriving through the portal as room is made as all prepare themselves for a long foot march toward the lights on the horizon.