The Imperial Army of the Nilfgaardian Empire is, without a doubt, one of the best-trained fighting forces of the Continent. Boasting from the lower ranks to the higher nobles involved within the military, the men are well-versed in the art of combat. It's entirely under Imperator who leads it through a set of high-ranking officers under a Field Marshal.
During greater conquests and invasions, like the Northern Wars, the army is divided into groups, such as Center Army Group, East Army Group or Verden Operations Group. During the second of these invasions to the North, the army count was ca. 320,000, with 300,000 attacking the kingdoms and about 20,000 remained in the Empire to keep peace and defend core provinces in case of some unexpected turn in war.