In the period from 200BC to 120AD new lands were conquered by the Romans, and the Roman Republic and later the Roman Empire spread through Europe. Gradually, however, the strength of the Roman Empire declined. The fall of the Roman Empire was caused in part by the decline in power and effectiveness of its army, and in part by public health issues, as well as political instability with many different emperors. It has also been suggested that the economic impact of unemployment and inflation along with a decline in public morals and values weakened family life, upon which the Empire had been built.
During the period between Marcus Aurelius dying in 180 AD and Diocletian becoming emperor in 284 AD the army's Auxilia became disloyal and showed lack of discipline . When Diocletian became emperor the legions were split into smaller groups so that each general commanded fewer men. This greatly improved the moral of the army. Also frontiers were made stronger and provinces made smaller to stop each governor getting too powerful. After Diocletian's retirement more troops who were defending the borders of the empire had to be moved back to Italy because of civil war and rebellions. This meant the government had to pay even more money and soon the economy of the Roman Empire fell to pieces.
When Septimus Severus marched into Rome, defeated his rivals and became emperor, taxes were raised and prices went up. This increased the number of poor people. In 301 Diocletian tried to fix maximum prices for all goods and wages in the Empire . He made a long list that included everything from wheat and grains to mice and sparrows . This did not succeed though as goods stopped being sold in public markets where prices were controlled. Instead they were sold in secret sales which developed into an illegal form of trading known as the black market . When this did not work Diocletian accepted the ruin of the economy and retired not long after that. Slowly, due to inflation, more people became poor and were forced to live on the streets.
When soldiers returned back from fighting in Seleucia in 161 AD they unknowingly brought back a disease known as the Antonine plague. The plague killed up to one-third of population in some places and greatly weakened the army . In 180 AD Marcus Aurelius contracted this disease and died . Also, many wealthy Romans had water taken directly to their house through lead pipes. This made the death rate of healthy people quite high and some emperors were known to die from lead poisoning
One of the main contributing factors to the fall of the Roman Empire was the decline in quality leadership and management. The leadership and management of Rome was a strong asset in the times of the Roman Republic, Expansion of Rome and the early and middle stages of the Roman Empire. In 180 AD one of the last good quality emperors, Marcus Aurelius died, and in this year the Praetorian Guard in Rome sold emperorship to the highest payer . This started the decline in leadership and in during the next one hundred years Rome had 37 different emperors, 25 of which were removed from office by assassination . Diocletian became emperor in 284 AD. He was a dictator who brought the army and Empire under control by splitting the Empire into and East and West Half, making it easier to handle .
It was not long after Diocletian retired in 305 AD that Constantine became emperor. Constantine moved the capital of the Empire from Rome to Constantinople . The struggle against barbarian invasions continued and in 395AD Theodosius "the great", Constantine's successor, came to an agreement with the Goths. He gave them land inside the Roman Empire, in return the Goths would help the Romans fight against any further invaders . When Theodosius died the leadership of the Empire was split between his two sons. The western half was ravaged by invaders. The Eastern half then became the Byzantine Empire, an Empire which would last for over a thousand years . In August 410 AD, Alaric, leader of the Visigoths, sacked Rome thus ending the Roman Empire .
It was not one single one of these factors that contributed to the fall of the Roman Empire but rather the combination of all these factors weakening the Empire until it could no longer stand the constant pressure of the attacking barbarians. Lots of these factors are also evident in the collapse of other ancient civilisations and some can even be found in the present day.
