In ages past, Nova was ruled by a king. The king was always the lord of a great House, and ruled more as first among equals. The origins of the office of king are obscure, and its necessity is little questioned by Novan historians and intellectuals. Even in the Age of Steel, when Novans recognize no king, it is generally taken for granted that the natural or original state of man was to be ruled over by a king.
As Nova Primus is a very extensive landmass, the duties of the king were historically quite limited. The king was bound to protect the faith (meaning, in theory, both the Ecclesiarchy and the Mechanicus, although in practice the Ecclesiarchy often received the lion’s share of royal assistance), and to defend humanity against major threats such as ork Waaagh!s.
These duties were enforced by vows of fealty sworn by the lord of each House to the king. The exact content of these vows is known to have varied over the years, but they were always limited along the lines of defending the church(es) and mankind.
The office of king did pass from father to son, but in ages past the crown did pass from House to House (generally in bloody wars of succession). All agree that House Vaar has given Nova more kings than any other House, but all Houses except for House Rhinette have held the crown at least once in their history.
The era of kings ended in the Age of Iron. The exact date is not agreed upon, but all agree that the end of the Age of Iron is defined as whenever the last Novan king was overthrown, and this is generally accepted to have occurred at least 300 years ago. King Kaddar III Vaar was the last Novan king. During his rein, the Spire’s demands for tithe increased radically, and Kaddar III sided with the Ecclesiarchy over the protesting Houses. Such was the burden of the tithe that all six other Houses united against Kaddar and the white priests in a rebellion that eventually included many of House Vaar’s own vassal Houses. Though the rebels never took Stonehull, Kaddar III was betrayed by his own son. The power of the Ecclesiarchy would never recover, and although Kaddar’s son was allowed to assume the lordship of House Vaar, no king was crowned. The Age of Steel had begun.
According to various off-world personnel, Nova’s king was in fact responsible for administering (and defending) the planet as part of the larger Imperium, a state of affairs of which the rest of the world was ignorant. Polynikes Callistos has speculated that it is not unknown for imperial planetary governors to “go native.” It may have been the case that the kings of Nova belonged to a tiny number of people who knew of Nova’s true position among the worlds of the Emperor, but it is also possible that over time even the kings forgot this knowledge, or that it was passed from king to king in debased and mythologized form.
While custom gives a lord extensive powers of justice within his lands, and feudal vows may give him great power, lords are not kings. In ages past, Nova was rules by kings, who acted as first among equals among the lords of the great Houses. The main difference between a king and a lord is that the king of Nova was owed a certain degree of fealty by all Novans, even in the absence of an explicit feudal vow. In practice, the crown was a largely religious institution, responsible for defending and upholding the Ecclesiarchy and giving assistance to the Black Sisters.
The last king of Nova was Kaddar III Vaar of House Vaar, whose reign ended three hundred years ago. Kaddar III was overthrown by his fellow lords after instituting a wildly unpopular head tax to fund lavish sacrifices at the Spire. The revolt destroyed the monarchy and was a watershed event for the Ecclesiarchy, which has largely refrained from meddling in the Houses’ economics affairs ever since.