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Imperial Castrum (ロイヤル・駐屯地) is a fortified military camp stationed near the Katze Plains. It is used by the Imperial Army during the Annual Wars with the Re-Estize Kingdom.


Located near the Katze Plains, it serves as a marker for where the land of the livings bends near the unhallowed ground. During the Annual Wars, it served as the Imperial Army’s garrison base.

Originally, this place was intended to be the starting point of invasions targeting E-Rantel. That was to say, this massive castrum had been built with the intention of withstanding an extended siege by the Kingdom’s hundreds of thousands of troops.


The Magic Caster of Destroy Arc[]

Main article: The Magic Caster of Destroy Arc

Two months after the Baharuth Empire announced its alliance with the Sorcerer Kingdom to reclaim E-Rantel and the Katze Plains, six legions of the Imperial Army assembles at the Imperial Castrum. Nimble Arc Dale Anoch arrived there as well to forewarn the commanding officer, General Natel Inyem Dale Carvain to prepare a welcome for Ainz Ooal Gown. After giving him an imperial salute as a visiting Sovereign, Ain requested to be allowed to bring his forces to the base to participate in the war. Finding it permissible, Natel allowed him to do so. Soon after a force of five hundred Death Knights to emerge from a Gate.[1] It seems apparent that Empire's army at the Imperial Castrum had no intention of making the first move in launching an attack at the Kingdom's Army until Ainz successfully cast his super-tier spell to signal the start of war between both sides. Once the spell casting was initiated, he ordered his Dark Young creatures to slaughter the Kingdom's army until he issued one of them to head back to the Imperial Castrum. By the time his Dark Young arrived at the Imperial Castrum, it had spark mayhem with the Empire's army while others remain awed by the sight of the Sorcerer King's fearsome power. Ainz left the castrum with the Dark Young he ride on to seek out Gazef Stronoff, attempting to recruit him into the Sorcerer Kingdom's ranks. Unfortunately, after Gazef rejected his offer and died fighting Ainz, he declared to Brain Unglaus and Climb that the ruler of the Re-Estize Kingdom must recede E-Rantel to the Sorcerer Kingdom or else more carnage will reach their royal capital of Re-Estize. Afterward, Ainz left the battlefield with the summoned Dark Youngs, making his way back over to the Imperial Castrum.[2]

Layout & Features[]

The Castrum was built with huge logs that were nowhere to be found on the surrounding plains, with sturdy walls that denied passage to all in its vicinity. The shallow ditches that ringed it were carefully excavated and filled with sharpened stakes in order to ward against unintelligent undead.

It was built on top of a hill. This hill was not native to the Katze Plains but built up entirely through magical landscaping. This structure had been built over a period of several years.

The garrison could house all of 60,000 knights of the legions, which spoke volumes about the base’s size. This formidable castrum, as mighty as a fortress, was built on a piece of easily defended terrain.


  • The Re-Estize Kingdom had no countermeasure against this fortress. Though the nobles would unite during the Annual Wars they bickered over gains and manpower to launch a punitive action towards the base. Hence it was left alone unless it was an immediate threat to the nobles.


  1. Overlord Volume 09 Chapter 2: Preparations for the Battle
  2. Overlord Volume 09 Chapter 4: Massacre


Click on the images to enlargen them.


Re-Estize Kingdom
Re-Estize Ro-Lente Castle Magician's Guild Re-Blumrushur Re-Robel E-Naüru Re-Uroval E-Pespel
Baharuth Empire
Arwintar Grand Arena Imperial Castrum Ministry of Magic
Roble Holy Kingdom
Hoburns Kalinsha Loyts Prart Rimun Debone Great Wall Holy Kingdom Liberation Army Base
Sorcerer Kingdom
Great Tomb of Nazarick Log Cabin E-Rantel Katze Plains Carne Village Monument of Ruin Great Forest of Tob Abelion Hills Great Lake Underground Tomb
Elf Country
Crescent Lake Great Forest of Evasha
Dwarf Kingdom
Feo Jera Feo Berkana Feo Teiwaz Maze of Death Great Rift Feo Jera's Garrison
Other Locations
Eryuentiu Azerlisia Mountains Sea City Sasasharu Ruins Silent City Bown Swamp Rhynd Sea Sewage Treatment Plant Vadis Free City Quarry Tide Pool