In the introduction I made some claims -- that the Roman Empire
is unique in its continuous existence for almost 1800 years, and that
the
"Holy" Roman Empire, for at least some of its existence, could be
counted
as a continuation of the Roman Empire -- that are perhaps contentious.
To justify them, I here define my terms.
The Roman Empire is a state which
1. Is an empire. That is, a state which calls itself an Empire, or in which a centralized authority uses force to exercise a significant degree of political control over ethnically distinct provinces at a considerable distance (100s of km).
2. Contains within its territories the city of Rome (Italy), or New Rome, and assigns to that city a central role in the political life of the state. Here, New Rome is a city founded by an existing Roman Empire deliberately as a second capital on an equal footing with its first capital, and officially called New Rome. (There is only one New Rome, and that is Constantinople.)
3. Considers itself the successor to the original Roman Empire (that founded in Italy in the 4th century BC).
4. Is a successor to the original Roman Empire, in the sense that it
has political continuity traceable through its predecessors back to the
original Roman Empire. This entails
a) the continuation of significant aspects of central government by
the state, and the general recognition of that state as the sole
successor
of its claimed predecessor, and that a gap of less than two generations
(60 years) separates it from a predecessor that was a Roman Empire.
OR,
b) in the (unique) case of the creation of two Roman Empires by
deliberate
partition of one Empire into two (that centred on Rome and that centred
on New Rome), the continuation of significant aspects of central
government
by the two new states
OR
c) in the (unique) case of creation of two Roman Empires by
re-establishment
of an Empire centred on Rome, the continuation of significant aspects
of
government by the new state and the formal recognition by the Empire
centred
on New Rome of the political equality of the new state.
According to this definition, the political history of the Roman Empire is as follows:
The Roman Empire began in 338 BC, when the republic of the city of Rome imposed its direct rule upon the former league of Latin cities, which had hitherto been a free association dominated by Rome. Thereafter followed four centuries of great but steady expansion. Rome did not acquire an Emperor until Octavian became Augustus in 27 BC, but even then it remained a Republic in name, nominally under the rule of two Consuls for each year. In 330 AD the first Christian Emperor, Constantine the great, founded the city of New Rome on the site of Byzantium, soon to be known as Constantinople. By this time Rome itself had ceased to be the administrative centre of the Empire, or the place of residence of the Emperor. But Rome still held the Senate, and New Rome now had its own Senate too. Increasingly at this time the Eastern and Western halves of the Empire were independently governed, often with their own Emperors. The last Emperor to rule both halves as equals was Theodosius the great, who on his death in 395 bequeathed the West to his younger son Honorius, and the East to his elder son Arcadius.
Over the next 80 years, the Western Empire fell gradually to (mostly Germanic) warlords, while the Eastern Empire remained almost intact. By 476, when only Italy and a few nearby areas remained to the Western Empire, its last Emperor, Romulus "Augustulus", was deposed in an army coup by Odovacer, supported by the Roman Senate. Romulus' last act was to send a letter of resignation to his Eastern counterpart Zeno, along with the Imperial regalia, stating that there was only need for one Emperor now. For the next 60 years, "Greater Italy" had a curious status. Odovacer and his successors, the Kings of the Ostrogoths (Theodoric the Ostrogoth had invaded Italy with the blessing of the Eastern Empire in 488), were ethnically Germans. But they were in many ways Roman in culture, and maintained most of the Roman forms of government, including the Senate and the appointment of a yearly Consul (the Emperor in Constantinople appointed the other). Sometimes they were treated as rebels, sometimes almost as the equal of the Emperor in Constantinople, but they always maintained a theoretical subservience to him.
Unfortunately this delicate balance was destroyed when hostilities broke out in 536, due to the expansionist policies of the Emperor Justinian the great. By his death in 565, Italy, and much of the rest of the Western Empire, had been reconquered. But the Western Empire was not reconstitued. Instead the Senate in Rome and the office of Consul were abolished, and the whole Empire was ruled from Constantinople. Over the next two centuries most of the Empire in the East, and nearly all the Empire in the West, was lost to invaders. Rome and its surrounding lands continued to be part of the Empire, but in practice authority there fell on to the Popes. Under dire threat from the surrounding Lombard kingdom, the Pope changed his allegiance from the Eastern Emperor to Pepin, King of the Franks, in 755. In return, Pepin defeated the Lombards and gave the former Imperial lands in central Italy to the Pope, forming the Papal States (756-9) under his protection. The final act was on Christmas day of the year 800 in Rome, when Pope Leo III crowned Pepin's son Charlemagne "Emperor governing the Roman Empire". From the point of view of Constantinople, the Pope had no authority to make an new Emperor in the West, so the "donation of Constantine" was forged (presumably by someone within the Roman Church) to justify that authority.
Charlemagne's elevation to Emperor was finally acknowledged by the Eastern Emperor Michael I in 812. Although the easterners called him "Emperor of the Franks" rather than "Emperor of the Romans", Charlemagne's new seal contained the words "Renovatio Romani Imperii" and his Empire was, by my definition, a restoration of the Western Roman Empire. Indeed, at this time, when "Christian" was almost synonymous with "Roman", the two Empires together ruled almost all of Christendom. Charlemagne's successors lacked his greatness, and the Empire he had founded diminished until by 888 it was reduced to the northern half of Italy. After 924 its rulers ceased to claim the Imperial title, and instead called themselves Kings of Italy. In 962, the King of Germany, Otto I, took the Kingdom of Italy by force at the request of Pope John XII, and was crowned Emperor in Rome. As a repetition of the coronation of Charlemagne, this act reconstituted the Western Roman Empire, after a gap of 38 years. It was not referred to as the Roman Empire until 1034, and was also called by many other names, including the Holy Empire after 1157, and the Holy Roman Empire after 1254. This last is a convenient name to use for the Western Empire from the time of Charlemagne on.
The Eastern or Byzantine Empire (another name of convenience) was
dissolved
in 1204 when the fourth crusade was diverted by Venice to sack
Constantinople
and place a "Latin Emperor" on the throne. The small and weak "Latin
Empire"
in Constantinople lingered on until 1261, but cannot be considered a
Roman
Empire by my definition because it did not continue any significant
aspects
of government of the Byzantine Empire. There were several genuine
successor
states to the Byzantine Empire, and one (centred on Nicaea in Anatolia)
was eventually able to defeat its rivals and the Latins and reconquer
Constantinople
in 1261. By this act, the Byzantine Empire, under Michael Paleologus,
was
reconstituted, after a gap of 57 years. It lasted until 1453, when the
last Emperor, Constantine Paleologus, died fighting the Turks pouring
into his capital.
The Holy Roman Empire, meanwhile, ended not with a bang but with a whimper. In 1278, Pope Nicholas III had declared the Papal States politically independent of the Empire. In 1282, the Emperor Rudolph of Hapsburg, decided not to contest the issue. The city of Rome was no longer part of the Empire and so, by my definition, it was no longer a Roman Empire. It is even arguable whether it was really an Empire by this time, as the control the Emperor exerted over most of the mini-states within the Empire's boundaries was minimal. By 1648 it had lost its territories south of the Alps, and had become the Holy Roman Empire of the German Nation. In 1806 the last Emperor Francis II abdicated (in the face of Napoleon Bonaparte's armies). In its act of auto-dissolution, the Empire referred to itself as the German Confederation, recognizing the truth in Voltaire's damning witticism that it was neither Holy, nor Roman, nor an Empire.