The principal armed forces of the King-Emperors of the Mephitist Empire; among other personnel, Westersloe Winterbough V was a member.

The "I&RA," as it is often known, had its origins in the armies of King Irenaeus Lacktail, though his armies were more of an ad-hoc affair, raised and dismissed as circumstances warranted. With the formal creation of the Mephitist Empire, the need for a formal standing and permanent army was obvious.

The I&RA was commanded by a Marshal; in the reigns of both King Adler the Prudent and King Gawain, this was the younger brother of King Adler, Roland Sartoriusson. The army was composed of a number of infantry and ant-borne cavalry regiments, which generally rotated among the many posts maintained throughout the Empire. The most prestigious regiment was the Household Cavalry Regiment, commanded for many years by a Colonel Briarrose, a highly decorated mephit.