Dominium mundi / Universal monarchy / Universal power

Dominium mundi

Dominium mundi is an idea of universal dominion developed in the Middle Ages. Inspired by the memory of the Roman Empire, dominium mundi implied the recognition of one supreme authority, which generated a prolonged political and spiritual struggle between imperial and ecclesiastical power.

https://en.wikipedia.org/wiki/Dominium_mundi

Universal monarchy

In Europe the expression of a Universal Monarchy as actual total imperium can be seen in the Roman Empire, and as the predominate ‘sole sovereign’ state during its Byzantine period, where the Emperor by virtue of being the head of Christendom claimed a sovereignty over all other kings even though in practice this could not be enforced. The Byzantine conception went through two phases, initially as expounded by Eusebius that just as there was one God so there could only be one Emperor, which developed in the 10th century into the conception of the Emperor as the paterfamilias of a family of kings who were the other rulers in the world.

https://en.wikipedia.org/wiki/Universal_monarchy

Universal power

In the Middle Ages, the term universal power referred to the Holy Roman Emperor and the Pope. Both were struggling for the so-called dominium mundi, or world dominion, in terms of political and spiritual supremacy.

https://en.wikipedia.org/wiki/Universal_power