For a long time I was under the impression that Edward Gibbon's Decline and Fall of the Roman Empire did what most modern histories of the Roman empire do - end with the deposition of the western emperor Romulus Augustulus in AD 476. But Gibbon doesn't. He takes the story all the way up to the fall of Constantinople to Mehmet the Conqueror in 1453.
Good for Gibbon, I say.
As a school child and undergraduate, I was always taught that the Roman empire ended in the fifth century AD. The Byzantine Empire centred on Constantinople was something different, something belonging to the different field of mediaeval history (and an aspect of mediaeval history I learned almost nothing about at school, as the lessons I had were only interested in the history of England). But as I've got older, I've come more and more to the conclusion that this is simply wrong-headed, a distorted western viewpoint. The bottom line is that the Byzantines did not see their empire as anything different. All the emperors up to Constantine XI saw themselves as heirs of Augustus. And they were all addressed as 'emperor of the Romans'. To see the emperors in Constantinople after AD 490 as being different, and to sneeringly describe their rule as a mere 'continuation' of the Roman empire, is a view that privileges the western European experience.
More sophisticated commentators tend to talk of 'the fall of the western Roman empire'. But even that seems to me a misnomer. It implies that the western empire was a separate political state. People talk of the 'formal division of the empire' on the death of Theodosius the Great in AD 395 (Francis Pryor does so in his recent book Britain A.D.).
But no such formal division ever took place. What happened was that Theodosius left the empire jointly to his sons Arcadius and Honorius. Arcadius' sphere of responsibility was in the east, and Honorius' in the west. But they were joint rulers of the empire, and legislation promulgated by one applied in the other's territory. It had been the case for much of the previous century that there had been more than one Augustus (the term used by then to designate the emperor), and that each Augustus had certain geographical responsibilities. But the empire remained one, and could in theory be reunited at any point. For the eighty years after Theodosius' death it wasn't, and each eastern and western emperor was replaced by another emperor whose responsibilities were only in half of the empire. Yet there remained co-operation, and each emperor took an interest in the appointment of his colleague. In particular, the eastern emperor, clearly the senior, took close concern over the appointment of the western Augustus, and anyone wishing to be western emperor who couldn't get Constantinople's approval wouldn't last long (I don't know of any evidence of the reverse taking place - when the eastern emperor Theodosius II died in AD 450, no-one seems to have been much concerned about any theoretical claims that Valentinian III in the west might have had, and Valentinian himself doesn't seem to have pressed them). So, there were two emperors, but the empire remained one.
What happened in the twenty years after the assassination of Valentinian III in AD 455 was that various Germanic warlords in the west tried to get their puppets appointed western Augustus, sometimes succeeding, but sometimes having to accept the eastern appointee. None of these lasted very long, because of a military crisis in the west. Sometimes, there were a few months when wasn't a western Augustus. But this wasn't considered a desperate problem, because there still was an emperor ruling the empire, and he would appoint a colleague when it became necessary.
This chaotic period is generally considered the 'fall of the west'. Clearly, there was fragmentation and loss of control in the western provinces, to the extent that by AD 476 the empire's authority in the west extended little beyond Italy. However, it seems to me that seeing the processes of the collapse of the Roman way of life in the western provinces as the fall of a separate western empire is a misleading way of looking at it. What was happening was not the fall of the western empire, but the empire losing control of the western provinces, being unable to sustain itself at its current size, and contracting until it stabilized around what had by then become the centre of imperial gravity. Many of the problems associated with understanding the fifth century go away if looked at from this perspective.
It has been noted by scholars that any explanation of why the western empire fell has also to explain why the east survived. But look at the empire as a unity, and ask the question, 'why did the empire lose control of the west?' and it becomes easier, I think. As the political centre of the empire moved east to Constantinople, so control of the western provinces became ever more problematic, until finally it collapsed altogether. As Richard Baker has reminded me, Constantinople would have been more concerned with the Persian frontier. A collapse in Gaul posed no immediate threat to Constantinople. A collapse in Mesopotamia and Armenia, on the other hand, would raise the spectre of Persians rolling up Anatolia (and a collapse on the Danube would similarly be a more immediate problem than anything in Germany or Gaul). Of course, the western Augustus would have had a different view, but, as noted, the western Augustus was the junior imperial partner.
Roman control in the western provinces did eventually end. But not in AD 476. That year did not mark the end of Roman control over Italy (never mind that Justinian would reconquer the peninsula in the next century). Yes, the 'last emperor', Romulus Augustulus, had been deposed, and the man who did it, Odoacer, did not seek to get a replacement appointed. But he still acknowledged the sovereignty of the eastern emperor, Zeno, who even forced Odoacer to issue coinage in the name of Julius Nepos, Augustulus' predecessor, who lived on in exile in the Balkans. So really Nepos was the last western emperor.
I don't want to minimize the importance of what happened in AD 476 (or AD 480, when Nepos was murdered). It was a significant change in the way Roman rule was exercised in the west, a transformation from direct rule to vassal kings and one which was largely forced upon the empire rather than being of its choosing. But it was a change, and not the end. Roman rule was flexible enough to accommodate vassal kings, and this had been a method used throughout Roman history (so, maps of the extent of Roman rule at the empire's height ought to - but rarely do - include the Crimea, where Roman emperors determined the rulers of the Bosporan kingdom). That this had now happened to the metropolitan territory of the empire must have been a psychological blow, but I think it shows the strength of the empire that it could survive such a blow. No western emperor was appointed after Nepos' death, presumably because Zeno felt that the new system and the collapse of Roman control through much of the western provinces meant that one was no longer needed (and I daresay even he thought 'for now', and was open to restoring the post should the need arise). Odoacer, and then Theoderic the Ostrogoth, acted as Constantinople's servants, in much the same way as the western Augustus had, save that these men were clearly not the emperor's equal. One can certainly argue that the acknowledgement of Roman authority by these Germanic kings was somewhat nominal, and that largely they did what they wanted to - certainly Justinian felt that the situation wasn't acceptable, and re-established direct rule. But one shouldn't completely ignore the lip-service paid, and the fact that clearly Odoacer and Theoderic felt that they had, or indeed needed, to be seen to act in the emperor's name.
So, the Roman empire did not fall in AD 476, but changed. The emperors continued to have authority in Rome - when the Pantheon was given to the Pope in the early seventh century, it was the emperor Phocas did so, on a visit to Rome. Roman authority in the city was not really ended until the eighth century, and a Byzantine presence in southern Italy lasted until the Normans drove them out in the eleventh century. The Roman empire's fall came in AD 1453. When Charlemagne was crowned Augustus by Pope Leo III on Christmas Day AD 800, from which event the Holy Roman Empire began (something else about which I was shamefully not taught in history classes at school), it was not the revival of a title and empire long departed, but a direct challenge to an empire that still existed. (In fact, the throne at Constantinople was occupied at the time by the Empress Irene, which in Leo's eyes meant that it was empty, so he elevated the Frankish king in order that there should be an emperor. The Byzantines told him to get stuffed.) William the Conqueror, Robert the Bruce and Geoffrey Chaucer all lived in a world where the Roman empire still existed. Richard the Lionheart even went there, and Harald Hardrada, loser at Stamford Bridge, worked for the Romans for a time. Remember that, when you next think about the Romans, and how remote they seem.