[bwanab]

It should be noted, though, that by the time of Basil II in the 900s, the Eastern Roman Empire (aka Byzantium - a name neither they nor anyone else uses until the 19th century) had again become the most powerful military actor in the western world.

[fakedang]

And then they got rekt in Manzikert, 1071 AD. 46 years after Basil II's death.

Let's not kid ourselves, the Byzantines had far more underlying problems throughout its history and only mostly survived by a.) the walls of Theodosius, and b.) bribing away potential invaders and getting others to fight their wars.

[wqaatwt]

Generally battles like Manzikert or similar events were only as disastrous because they were inevitably followed by internal chaos and civil wars.

The free for all nature of the succession meant that whenever the empire was facing major difficulties (i.e. because the emperor was incompetent or due to factors he couldn’t really control) every general or noble within the eyesight of the throne thought that he should have it.

Turkish gains after Manzikert itself were limited and much of the imperial army survived. Of course it marched straight back to Constantinople for its commander to appoint a new emperor (since Romanos IV was captured by the Turks).

Then the Romans kept fighting each other for years while entire Anatolia was gradually lost.

Manzikert was a disaster but they certainly had enough resources to bounce back (i.e. it was certainly not worse than Cannea)

1204 also started as coup attempt by the Venetians to put the son of a former overthrown emperor on the thrown.

[bwanab]

Yes, Basil II had the unfortunate legacy of not leaving an heir at a very bad time. The Romans of the Eastern Empire had their problems but mostly just a continuation of the old Empire: dynastic jealousy and external enemies. As enfeebled as their last 300 years were, they were pretty unique in having lasted almost 2 millennium.