When did the Roman Army lose it\'s...

[Robert Vermaat]

But this creates another interesting question: why did the state fail? I personally think that the conquest of Africa by the Vandals, which cut off the food supply of Italy, was the most important cause. Within six years, the tax department had been abolished.

Of course we could then ask ourselves why it was no longer possible to secure food supplies from Egypt.
Myself, I think that the Roman political system was mainly to blame. With no effective way to secure the succession the system was open to abuse from nearly every general. Had the 3rd century seen a similar plight, the Dominate had devolved into a similar weakness by degrading the actual power of the emperor. Instead it was the Patrician (aka 'man behind the throne') who wielded real power if only when he dominated the emperor, which became easier end easier in the West. Until, at some point, the West was back in the situation of the 3rd century, with warlord battling warlord, using Roman as well as non-Roman troops, making it more and more difficult for the population to see the difference (and hence to secure their allegiance to ‘Rome’). Without a clear identity of the government, the military and the population easier accepted non-Roman warlords and troops, as long as these fought for ‘the good cause’. An army of Goths under Alaric could hence be style a ‘Roman’ army, instead of a barbarian invasion force. The Vandals conquering Africa were not distinguished as a barbarian horde either.. In the end, there was no real difference between Roman and non-Roman, and the empire became defunct. In the East, they managed to avoid this with a stronger imperial government and a move away from an easy integration of non-Romans into the higher echelons of government and the army. Not a total exclusion, mind you, but a different system than the West employed. The Patrician never achieved as much power as he did in the West, and the emperor remained a lot stronger.