“Dinanzi a me non fuor cose create se non etterne e io etterna duro.”
“Before me nothing was created but eternal things and I endure eternally.”1
FROM THE FALL of Rome in A.D. 476 to the crowning of the Frankish leader Charlemagne by the pope on Christmas Day 800, the former territory of the Roman Empire was successively flooded by waves of barbarian invaders from eastern and central Europe. Literacy, trade, and simple security dramatically receded toward the Mediterranean. By the end of the first millennium, however, the central island of the old empire had re-emerged, lapped by Muslim conquests in Spain and North Africa, Norse settlements from the North Sea and Baltic coasts to Sicily, and the incursions of tribes from the eastern steppes that had come as far as Rome and then ebbed to the edges of Vienna. The remaining center, composed of the lands colonized by Germanic tribes in what is now France, as well as Italy and central Europe, huddled together, its populations largely Roman Catholic in religion, and its local rulers the dynastic tribal successors of the Germanic invaders. Within this center two parallel structures developed: the universal Church spanning local cultures, and the fragmented feudal system of local princes. The legal relations of these two entities were in principle separate: the Church system of religious, educational, bureaucratic, and charitable life co-existed with the military and proprietary prerogatives of the nobility, though in fact the feudal administrative structure depended on Church personnel, and the Church was itself a landowner of immense wealth and political presence.
The defining legal characteristic of medieval society was its horizontal nature, reflected across these two pervasive dimensions of ecclesiastical and feudal power. From a modern and secular perspective, these two systems are difficult to imagine as operating simultaneously. Medieval society, however, was not divided into separate states, with each prince a sovereign within his own territory, ruling hierarchically all within that territory and no persons or territories remaining outside the domain of some prince. On the contrary, political society was organized into four co-existing functional sectors: the nobility, the clergy, burghers, and peasants—although some of these sectors were themselves organized vertically, and the authoritative heads of one sector might have had a certain legal authority over the members of the other sectors, as, for example, the Church had jurisdiction over wills and marriages in all sectors. Vertical power, however, was horizontally limited; for example, while a king could demand military service from the feudal vassals who were obligated to him, and while some of these lesser lords owned land to which peasants were attached, a king had no direct authority over his vassal's peasants. Similarly, the urban stratum of medieval society, comprising artisans, merchants, and townspeople of various functions, was in many aspects of life independent of both the clergy and the nobility. A great number of these townspeople were Jews, who though often operating under severe civil restrictions, were largely autonomous. It is to these cities that we owe the concepts and practices of trade, manufacturing, banking, and the organizations of guilds. Some cities were self-governing; some were under princely patronage.
In this diverse commercial environment the need for legal norms is hardly surprising, but what was it about medieval Europe that made it the birthplace of the state system and its attendant norms of international law, when there were many other diverse, commercial environments—the Levant, the Far East—where this did not happen?
First, the medieval church provided a bureaucracy that encouraged regularization across many diverse cultural communities, and also was able to lend itself to the various political authorities in order to supply an administrative apparatus for their needs. The word “clerk,” which we associate with a governmental and legal establishment, derives from “clergy” and the practice of filling administrative posts with churchmen. Second, and more important, the two-dimensional nature of medieval Europe meant that the universality of Christendom was coextensive with the radically diverse and disparate ethnic, tribal, and cultural mix. In other cultures only one of these elements prevailed, either the imperial or the fragmentary. In the case of an imperial hierarchy such as medieval China, relations with outsiders always remained just that: no “society” could develop within which they were included. This was the experience of the medieval traders in the Far East and with the Muslim courts. In the case of the diverse but fragmented societies cohabiting the same territory without an overarching superstructure, their very proximity tended to exaggerate conflict and prevent a common culture from developing. This was the case with the pre-Moghul Indian states. In both cases very advanced cultures failed to develop a state system and an international law because neither ever developed an overarching international culture.
In medieval Christendom, however, a universal, overarching institution existed that provided a society of diverse and competitive princes with both the means and the motive to develop a body of comprehensive legal practices. In the first place, legal rationales could bolster a prince's claim to territory or prerogatives. In a system of states without an overarching structure, there was no appeal to higher authority; in Europe, appeal could be made to the Church. Moreover, the omnipresence of ecclesiastical dominion often provided a motive for resistance to that dominion and the availability of legal arguments provided a resource to be deployed against the Church without having to reject ecclesiastical authority per se. As Adam Watson has put it:
The… legal justification for territorially defined realms made it increasingly easy for kings in the west to defy a particular pope (or in some areas emperor) though without formally repudiating the universal authority of these offices.2
In the second place, the superstructure of Christendom was itself an international legal culture. Popes were elected by cardinals from many different localities, and the Holy Roman Emperor was chosen according to the votes of the diverse electoral princes of the empire, including three archbishops.* It has even been asserted by some historians that the origin of the constitutional idea of a separation of powers lies in the struggle between papal and temporal authority, and the argument that the Church should determine the law as a guide but rely on independent lay rulers to execute and apply these rules.
Finally, the universal scope of the Christian community imposed restraints on a prince's reasons for going to war. Wars among Christians needed a legal justification. It is instructive to compare Aquinas's rules as to what constitutes a just war, addressing as he was a society of diverse princes, with those of Augustine, who spoke to an imperial audience. Aquinas's rules are an effort to “enhance the security of legitimate possession.” Indeed we can trace the current preoccupation in international law with justification for war to this period when it was the aim of the medieval Church to limit the use of force to the maintenance of world order, where the “world” was Christendom.
War against non-Christians provided the exception to these efforts at limitation. Here also the unique combination of competing princes and a universal order militated in favor of a developing multinational culture. A crusade had to be proclaimed by the pope, and there were strict rules governing such proclamations as well as the relationships that obtained among the participating princes. The crusades are an example of this interplay between local identification and universality, one that is often misunderstood by a sort of anachronistic psychological Marxism that would expose them as a mere facade for plunder. As Christiansen has retorted:
To present [the Crusades] as… matters of interest disguised as matters of conscience… is too easy. It avoids the unavoidable question of why men who were never reluctant to wage war for profit, fame, vengeance or merely to pass the time, without any disguise or pretext, nevertheless chose to claim that certain wars were fought for God's honour and for the redemption of mankind.3
It is important to observe that war in each of the theatres of European expansion was sanctioned by papal authority: the reconquista of the Iberian peninsula, the efforts to recover Palestine and re-establish the Roman Christian kingdoms in the Near East, and the expansion north and eastward against the pagan Slavic lands. All of these were Christianizing missions, given legal warrant and therefore legitimacy in the eyes of other princes by the sanction of the Church. As we shall see, it was the withdrawal of the universal Church from its legitimating role, leaving in its wake a society of political entities that were unable to assert an objective legitimate status, that in part produced the modern state.
The princes of this period were not territorial in the sense of having a fixed settlement and identification with that locality and its people; that would come later. At this time, the sense of their subjects was too local to be national; and the princes' sense of themselves and their property was determined by inheritance and to a much lesser extent by solidarity with a particular land or its inhabitants. They were not the monarchs of nations. The Henry V who fought at Agincourt to recover his property on the continent is unlikely to have spoken the sentiments of a nationalist, Renaissance author like Shakespeare in exhorting his men. For Harry, yes; but not necessarily for England and St. George. Nor were these princes of states; rather they governed realms, each with a rudimentary administrative apparatus that was impermanent and fixed only to the person of the prince. As princes without nations and without states, they were in some ways well suited to give birth to what would become international law because they had legal relations with each other that required legal rules. Princes made contracts: the law of contracts for princes became the international law of treaties; princes made war and the international laws of war arose from the laws of torts and crimes among princes; the international law of territorial conquest and session arose from the laws of property and the inheritance of estates among princes.
On this distinctively medieval pattern is the present international law based. This accounts for many traits that persist in that law, as the law of the society of princes became the law of the society of states.