The Roman Empire did not fall overnight. In fact, it is historically incorrect to say that the Roman Empire fell in 476 AD, when the eastern half of the empire would be alive and well for one thousand years after 476 AD. There were various factors that would lead to the end of the western half of the Roman Empire. There are so many that there is no one real force or factor that can be pinpointed as the cause of the fall of the empire. Scholars have presented an extraordinary amount of theories, and corollaries to them, to the educated community as to explain the demise of the largest empire to date. Theories are primarily based on fact; however, historians must use an inductive method of assumption to make their theories work. The most commonly excepted theories are: invading northern barbarians, new Christian values, lead poisoning, plagues, failure to advance technologically due to use of slavery, inability to achieve a workable political system.
The Roman Empire came under increasing pressure from invading barbarian forces. The major breaking point of the Roman Empire came in the second half of the fourth century when ferocious warriors from Asia, known as Huns, moved into eastern Europe and in turn put pressure on the German Visigoths to move west across the Danube into Roman territory. The Goths were originally Roman allies, but they soon revolted and became enemies. The Goths sacked Rome in 410 AD and the Vandals, who attacked Spain and Northern Africa, sacked Rome in 455 AD. This theory, based almost solely on fact, is a direct and easy explanation of the fall of the Roman Empire. However, it is not the sole reason for the demise of Rome.
New values had entered the Roman world and had a strong presence in Roman society in the third through fifth centuries in which Rome would fall. Christian values of love, peace, and anti-violence did not sit well with Christians who lived in an empire built upon a strong army. When Christianity gained prominence in the Roman world, many disliked the idea of conquering and war. Also, the Christian emphasis on a spiritual kingdom undermined Roman patriotism. Many non-Italians, not just Christians, gained prominence in the empire, which led to a decline in traditional Roman values.
Some Historians have suggested that the use of lead pipes and cups created reduced mental capabilities. Other historians think that plagues devastated the Roman population. The use of slavery in the Roman Empire could have reduced the roman advancement in technology because work was based on manpower, not the power of simple machines. When other civilizations could produce the same amount of product with less manpower, Rome was left in the dust. Technology would eventually create such a gap that Rome would not have enough slaves to match it. The inability of Rome to create a means of succession and a workable political system can also be tacked onto the list of reasons for its demise. Emperors were put on the throne by armies. The emperor was in power as long as he kept the army happy and the army did not lose to another army.
The Roman Empire was the largest empire in antiquity. Using their practical skills, the Romans achieved great heights that would continue to be used in future society. There is no one reason why the empire fell. The moral of the story is, history is a web of relationships, causes, and effects. No single explanation will suffice to explain a single historical event.