Royal Army

Royal Army (王国軍) was a grand military coalition of the Re-Estize Kingdom. It pooled the combined might of the various feudal lords to combat the annual incursions of the Imperial Army.

Background
The Royal Army is mostly composed of militia. Its soldiers are mostly just drafted peasants, they receive a government-issued weapon, no armor and extremely sparse training. The Kingdom usually levies two-hundred thousand men to fight the Empire, but it can levy more if need be.

The Undead King Arc
King Lanposa III sent Gazef Stronoff and his group of warrior troops to investigate and eliminate imperial soldiers who are raiding several village in Kingdom's territory. It was around this time that Gazef came face to face with a mysterious magic caster who made his presence known by the name of Ainz Ooal Gown in Carne Village.

The Dark Warrior Arc
During the Cemetery Incident, the undead army assaulted the gate of E-Rantel. The guards try to defend it but overwhelm by their sheer numbers. Momon's group arrived and breakthrough the undead hordes and saving the surviving guards.

The Men in the Kingdom Arc
The Royal Capital of the Kingdom came under attack by a demon known as Jaldabaoth and his army of demons, who came to the city to look for a powerful magic item. A large coalition of the Kingdom's adventurers and soldiers were brought together by Princess Renner and Lakyus Alvein Dale Aindra while being aided by the King himself, Gazef and his warrior troops. In addition, Marquis Raeven brought his private troops in order to stop him.

The Magic Caster of Destroy Arc
The Royal Army began their annual war with the Baharuth Empire in the Katze Plains. However, the Empire this time had decided to form an alliance alongside Nazarick in order to acquire the territory of E-Rantel. With the war looming closer as one month passes by, the Kingdom then sent an army of 250,000 to the Katze Plains while an additional 5,000 troops led by the crown prince to head to Carne Village for information about this mysterious magic caster surrounding Ainz Ooal Gown.

When the war was about to start, the battle was over before it even began when most of their army were devastatingly wiped out by Ainz and his five Dark Youngs.

Strength
The Royal Army was a grand military venture that drew conscripts from all regions of the Re-Estize Kingdom. However, individually the soldiers that composed of the army were weak farmers. Its only advantage was using sheer force of numbers to achieve victory against its foe.

Majority of the conscripted men in the Kingdom's Army would be at most level 2. Trained soldiers hired and under the service of the nobility would be around level 10.

Trivia

 * 50,000 militia soldiers are needed to stand against one legion, which consists of 10,000 trained knights, from the Imperial Army of the Baharuth Empire.