Operation Gehenna

Operation Gehenna was a campaign of Demiurge to allow Nazarick to place a foothold in the New World.

Background
After the Great Tomb of Nazarick has somehow been transported to the New World, Momonga and Demiurge went together outside to investigate. Ainz Ooal Gown (known as Momonga at the time) and Demiurge were amazed by the beauty of this world and the two pondered if they may have some sort of purpose for being here. At that moment, Momonga lightheartedly mused that the reason could be for them to take over.

Although that was merely a joke by Momonga, Demiurge took his words as literal. Following the day when Momonga rechristened himself as Ainz Ooal Gown, Demiurge informed the denizens of Nazarick on what their king has told him. Everyone gladly accepted it and swore to make Ainz Ooal Gown's dream a reality.

Much time has passed, Ainz Ooal Gown and Narberal Gamma had traveled to the New World and posed as Momon and Nabe of the Adventurer team, Darkness. They had built a phenomenal reputation, earning the respect of this world's inhabitants. Meanwhile, Demiurge has concocted a plan to further reach that goal and chose the Re-Estize Kingdom as the perfect tool.

Tsuare Rescue Mission
Sebas Tian and Solution Epsilon had been living in the capital, acting as spies for Ainz and were working undercover to gather information. During that time, Sebas discovered a young slave girl named Tuareninya Veyron and took her in. This drew the attention of Eight Fingers and after a series of events which lead to the capture of their subordinates, the organization decided to kidnap the Tuareninya to lure Sebas out to be killed for his defiance against them. Ironically, their latest scheme proved to be defiance against Sebas's master, Ainz Ooal Gown who commanded his Floor Guardians to hunt the criminals down like the animals they were. Sebas was joined alongside another party who also were also determine to bring Eight Finger down. The party comprised of Brain Unglaus, Climb and Lockmeier. Together, they confronted Eight Finger's security forces, Six Arms. Sebas single handedly killed five of them while Climb managed to defeat the remaining one. The team successfully rescued Tuareninya and crippled the criminal organization.

Demonic Disturbance
Although Eight Fingers were defeated, a new threat arose. Some time ago, Demiurge became aware of both the rise in criminal activity and the corruption within the kingdom's nobility. He saw them as an opportunity for Operation Gehenna and Tuare's kidnapping was the perfect excuse to carry it out.

Operation Gehenna was to have an army of demons invade the capital. The goal was to carry out a series of violent and destructive acts that will forced the Kingdom's Royal Army to intervene. When the kingdom's forces will proved unable to fight off the demons, Momon will enter the battle and successfully repel the invasion.

Meanwhile, Mare and Entoma had just finished abducting one of the Eight Finger's high ranking leaders. Mare left with their captive while Entoma stayed behind to finish off what remained. This lead to Entoma have her encounter with Blue Roses who nearly had killed the combat maid if Demiurge hadn't intervene and saved her. Demiurge, under the guise of Jaldabaoth made short work of the Adventurers, killing two of them in the process.

Coinciding with that battle, Darkness had just arrived at the Royal Capital to help suppressed Eight Fingers. Momon sensed Demiurge in battle and understood this to be part of his Floor Guardian's plans. He helped the remaining Adventurer, Evileye from the demon in order to throw off suspicion and allow Jaldabaoth to escape. After that, the Flames of Gehenna started to appear. The Operation has begun.

Darkness and Evileye met up with Princess Renner's forces. A plan has been made for a majority of the Kingdom's army and the Adventurers to fight off and stall the demons. While this happened, a small team consisting of Momon, Nabe and Evileye will enter the heart of the disturbance and defeat the demon's leader, Jaldabaoth.

The Re-Estize Kingdom struck back. Lead by Blue Roses, Gazef and members of the Royal family, the inspired Royal Army and Adventurers managed to wiped out most of the demons. Momon, Nabe and Evileye attacked Jaldabaoth and his maids and won after Momon brought Jaldabaoth to his knees. Before Momon could deal a finishing blow, Jaldabaoth bargained with the Adventurer. The demon revealed that he has an additional army standing by who will attack the capital in case of his defeat but if Momon spared his life, the demons will leave Re-Estize. Momon agreed and the invasion ended.

Aftermath
Operation Gehenna proved to be a success. Due to the Royal's Army inability to repel the invasion and the nobles who cowardly hid away from the battle, public opinion towards them were dangerously low. Instead, the citizens praised Momon for bravely saving the Re-Estize Kingdom from ruin. This made easier when the take over of E-Rantel took place some time later.

The forces of Nazarick has subjugate Eight Finger's chain of command. After enduring torture, the leaders willingly submit to their new masters. With that, Nazarick will used Eight Fingers to carry out their underground activities and further conquer the Re-Estize Kingdom.