Was the fall of Rome inevitable?

There is tremendous scholarly debate on this very
question; particularly in the last few years. The major factor in the fall of Rome was,
of course, the Barbarian migrations. ("Barbarian" was a term originating with the
Greeks, who said that the language of the German tribes sounding like the sounds of
sheep.) The Roman Empire had grown so large that it's borders were tremendous, and
difficult to patrol. Now, let's muddy the water a bit. In the year 376 (one hundred
years before the end of Empire) the Romans allowed the Goths to cross over to escape
from the oncoming Huns. This in essence opened Pandora's box. The Goths continued to
stream over, and occupied Roman lands. Needless to say, they did not pay Roman taxes,
which reduced the Empire's income. The Huns themselves were a factor. The Romans had a
tenuous relationship with the Huns under Attila, which mainly consisted of the Romans
buying them off.

Then there was internal strife within the
Empire. Roman armies, since Julius Caesar, were loyal to their commander, who typically
(but not always) was the Emperor. (Another little known factor: the Emperor himself was
known as the "Augustus," his successor as the "Caesar.") During a time of dissension,
there were as many as four claimants to the throne, all supported by their troops. Out
of 27 Emperors, only one actually died of natural causes. The others were either
murdered or committed suicide.

To muddy the water even
further; Germanic tribes often fought in the Roman Armies as mercenaries. They often
sided with one General or another, generally with the highest bidder. Finally, when a
General named Orestes installed his son (a feeble minded teenager) as Emperor, (Romulus
II Augustulus) the Germanic General Odoacher put an end to the nonsense by having
Orestes put to death, and forcing Romulus to abdicate. He then forwarded the crown and
purple robe of the Emperor to the Emperor in Constantinople with a letter that he was
the sole Roman Emperor now.

So, the variables would be
internal dissension, Germanic migrations (invasion is probably too strong a word) the
pressure created by the Huns, and the sheer size of the Empire. Could it have been
prevented? Probably, but to do so, the process would have had to be modified at least
100 years before the actual collapse.

Several excellent
sources you might consider: Adrian Goldsworthy: How Rome Fell, Death of a
Superpower; and also Christopher Kelly, The End of Empire: Attila
the Hun and the Fall of Rome.