Sorcerer Kingdom's Covert Invasion

Sorcerer Kingdom's Covert Invasion was the invasion of the Re-Estize Kingdom by the Sorcerer Kingdom during the conflict between the two nations. As the name implies, it was done covertly, with the Kingdom having no idea that war had broken out.

Background
Upon Albedo successfully "declaring" their date of invasion during their formal deceleration of war against the Re-Estize Kingdom in approximately one month from their deceleration, the Sorcerer Kingdom had in fact already sent out their armies to invade and conquer the Kingdom's northern and eastern territories and lands while completely leaving the western Area that contained the Royal Capital unharmed in order to further throw off their enemies from their actual activities.

This move was done under the suggestion of the Floor Guardian, Cocytus who had suggested it in order to isolate the Royal Capital from its remaining Allies. Cocytus' idea was met with approval by the Sorcerer King and his two intellectual confidants, Albedo and Demiurge who wholeheartedly assisted him in the sidelines by forcing the some of the nobles to join the Sorcerer Kingdom and completely manipulate the flow of information in order to conceal their invasion from the Royal Capital.

Such a decision was likely also done due to the Sorcerer Kingdom's tactical insight on the fact that the Re-Estize Kingdom had already begun making secret plans with their neighboring nation of the Argland Council State to create an alliance to defeat them. Through their consistent conquering of the Kingdom's lands that contained the Council State's Borders with the Sorcerer Kingdom, Nazarick was able to successfully put a stop to any form of alliance between the two nations, whose border with the Re-Estize Kingdom primarily lied in its northern front. Later it was indeed confirmed that the Council and the Re-Estize Kingdom themselves were still in the middle of their secret talks to create the Anti-Sorcerer Kingdom Alliance, talks that were thus then completely halted by the Sorcerer Kingdom's successful conquest of their borders with the Council State. Not only that but even the War's reason itself that basically made the Kingdom the ones responsible for sparking it effectively dissuaded the Council from further solidifying their alliance. The conquest of the kingdom's borders also successfully put pressure on the Council from interfering with their justified war of retribution against the Re-Estize.

Battles
The exact events of these battles are unknown. However, it mostly ended with the same result: the Sorcerer Kingdom's forces massacred all inhabitants of the territory they invaded.

The battles were so one-sidedly in their favor that the Sorcerer Kingdom even used it as an opportunity to experiment with new battle tactics. For example: in one battle, an army of Elder Liches was used to bombard a city in submission. Another was to airdrop undead using their recently acquired Frost Dragons. Mare, meanwhile, would simply use his nature magic to flatten entire cities and killing their population in one go.

Demiurge was in charge of information suppression to prevent the Kingdom's government from becoming aware of the situation. By using his Shadow Demons, the Floor Guardian was able to create a vast network that sought to it that no soul who entered conquered territories left alive.

Not all conquests ended in massacres, though, as Albedo was able to use the sheer infamy of the Sorcerer Kingdom to pursue several nobles into surrendering. One of these was Marquis Raeven, who would go on to point out other non-corrupt nobles to spare. These nobles would also aid with the information suppression by harboring refugees from fallen territories and preventing anyone from leaving their domain.

Aftermath
After successfully massacring and conquering a considerable amount of the Re-Estize Kingdom's territory in secret and successfully cutting off any form of transportation or communication with their remaining allied nation of the Argland Council State due to now taking control of the East and Northern halves of the Kingdom. The Kingdom's villages, cities, and towns were thus then massacred and slaughtered in mass to insure complete secrecy to the Sorcerer Kingdom's actual movements and successfully keeping the Kingdom's Western region that contained the Royal Capital oblivious to their invasion. However, despite the gigantic success and gains obtained by the Sorcerer Kingdom and the new experience and knowledge the Floor Guardians obtained in warfare from their trial and error experience destroying cities, villages, and towns, a few of Nazarick's denizens, who were sympathetic to the slaughtered humans, were secretly outraged by the barbaric actions done by their comrades and immediately made their discontent known during their plea for mercy for the innocent humans with their master regarding the invasion.