The political faction that Sigmar Heldenhammer is the patron deity of is based on what real-world empire?
The Empire (Warhammer) In Games Workshop's "Warhammer Fantasy" fictional universe, The Empire is one of the human political factions and armies, and is featured in many games and novels. In terms of location, language, culture, and society, it is clearly based on the real-world medieval Holy Roman Empire.
Consortium imperii Consortium imperii is a Latin term dating from the Roman Dominate, denoting the sharing of imperial authority between two or more emperors, each hence designated as "consors imperii", i.e. "partner in (exercising) "imperium"", either as formal equals or in subordination, in which case the junior was often the senior's designated heir—not necessarily the natural one—and successor. In theory, this arrangement served to share the burden of government and ensure smooth succession, as rivalry at these moments was a major threat to the stability of the Empire; however, in practice the net result was often more civil war.