[Wytwwww]

> Rome was sacked but recovered more than once

That's somewhat arguable. As far as we can tell the 410 AD sack was relatively organized and the violence was somewhat limited (by ancient standards at least..).

By 455 AD the population was almost 50% lower than it was before the first sack and the Vandal sack possibly also wasn't that brutal (no wholesale slaughter or destruction of buildings).

However the end of the 400s while the city still had a massive population by premodern standards (>100k) it was barely 10-20% of the population it had in ~100 AD and then it was almost entirely depopulated during the Gothic Wars and the plague. After that it didn't really recover until the modern era.

> what J. Ceaser did,

He wasn't exactly the first to do it and the precedent of leading an army into the city to overthrow the current government was well established by Caesar's day. Even Pompey himself basically used the threat marching his army into the city to force the senate to concede to his political goals.

Also it's not certain that the Rubicon thing was contemporary (of course legions couldn't technically cross the pomerium/sacred boundary of the city itself without disbanding and Caesar had no legal authority/imperium outside of his province to begin with).