The fall of Rome is probably the closest.
The integral part that collective guilt plays in our(and the West in general) demise ...is literally unprecented historically. The great irony is that we are far and away the most benevolent and powerful nation the world has ever seen...even considering our transgressions (see I even have to nod at our guilt reflex)...yet we are made to feel so guilty by those who resent us that we are willing to sell our own survival down the river to sate this guilt.
If Americans ever one day shed the burden of this weighty emotion in droves then we may yet have a chance to prevail. If not....then Libertarian or Conservative will matter little.