you are wrong that they did not have morals. Their morals were based on pride in their position etc.
Rome, truly speaking, if you refer to the Empire, only fell in 1453 -- the "Byzantines" called themselves Romaoi (Romans)
Rome would have fallen after Septimus Severus and the disastrous 2nd century when it had a number of different emperors.
the roots go back to the end of the 5 good emperors, to the last, Marcus Aurelius who made the mistake of leaving the Princep position to his actual son instead of adopting a worthy heir as had done Nerva, Trajan, Hadrian and Antoninus Pius. Commodus was a disaster and when he was assasinated, then came the year of the 5 emperors. This set the position for Severus who bribed his way.
From 193 AD right up until 284 and the reign of Domitian, the Empire was divided, had invasions by Germanics, had numerous barracks emperors who never even entered Rome etc.
Add to this, the problem of the 1st century when the Han Empire of China attacked and pushed the Xiongnu (huns?), who pushed the Scyths/Sarmatians/Alans, who pushed the Slavs out of their lands in the Ukrain, who pushed the Germanics out of their lands in Eastern Germany and Poland, who pushed the Celts, knocking on the doors of the Roman Empire.
A united Rome under Domitian and Constantine were able to provide a formidable resistance, but Constantine didn't follow Domitian's perfect succession rule (of 2 Augustii and 2 Caesarii) and also moved the imperial capital to Constantinople. Slowly Rome became less important, and by the 400s was a backwater. The Germanics slowly moved in and in many cases were terrified of the ones following them (huns).
Rome the city fell due to the
Re: 1 Rome had plenty of strong leadership, sometimes too strong.
Re: 2 Sure, when the central government fell because it could no longer levy sufficient troops or depend on its governors because they couldn't be trusted to act with the interests of the State, it became disunited. I think part of it is the familiar problem of the people no l longer trusting their leadership.
But how do you suppose they got to the stage that there was a crisis in confidence about the leadership, and the inability to levy troops in sufficient numbers? Again, part of the problem is that their birthrate was so low, they had to depend on foreigners and mercenaries to man their armies. Even their Generals, like Stilicho, were Germans or foreign nationals.
I'll submit to you that the low birthrate was partly a result urbanization and the public dole, but primarily the moral decline of the civilization as a whole. Roman Society no longer had that firm agrarian Latin peasant with a religious piety for the land and a patriotic fervour for Rome and her institutions, he had left the lands and gone into the cities because the agricultural production was done primarily by slave labor, while the numerous foreign wars fought by the Empire displaced him too. Also, many Romans settled in far-flung areas to the East and West, forming the basis of the Latin Civilization which survived the Roman Empire in time. So, the old Roman Legions were no more because the immorality of Roman society led to the decay of family life, the displacement of Romans from their traditions. And since the family had deteriorated, you no longer had a stable place for Roman citizens to be born, no virtuous young women to be suitable brides for virtuous young men to be the building blocks of the State as a whole; sounds familiar.
Domitian sealed the fall of Rome by subdividing the empire. At the time the policy was greatly beneficial, but the end result was disastrous.
‘A united Rome under Domitian and Constantine were able to provide a formidable resistance, but Constantine didn’t follow Domitian’s perfect succession rule’
I wouldn’t call the Tetrarchy perfect since it was not self enforcing and failed at the first succession. Otherwise a good summary of Romes’s decline EXCEPT that the Emperor Domitian was a tyrannical Emperor of the later first century AD. The Emperor who set up the Tetrarchy was Diocletian, who also set up the system used in the middle ages to bind folks to their employment and their parent’s employment, which led to serfdom.