After Honorius’s failure to protect Rome, the Roman army proclaimed several of its own generals to be emperor; Marcus (406/7 in Britain), Gratian (406 in Britain) and Constantine III (407-11 in Spain). Rome assumed at state of civil war and Constantine III further complicated the situation. He was named co-emperor in 409 AD, greatly reducing the strength of the autocracy. The eastern empire had been hard pressed at Hadrianopolis, but had been able to maintain its military strength. In the west, the military had to be greatly reduced due to the drop off in tax money, as a result of Honorius tax reductions as well as the civil strife of the empire. Coupled with the reduced military and the weakness of Honorius, the Romans were no longer able to keep the barbarians out of the provinces.
The true fall of Rome occurred in 410 AD at the hands of the Visigoths, under their king, Alaric. The city of Rome was sacked and the empire would never recover. The dying empire of the west would once again be left with one emperor, as Constantine the III abdicated and was later executed in 411 AD. Honorius would lead to a series of emperors that held power in name only, which would eventually end with Romulus Augustulus in 476 AD. The fifth century would be the last of the Western Roman Empire.
thx m8