The strategic mistake of Alexander the Great was that instead of uniting the 200+ Greek city-states into a permanent federal union, a kind of United City States of Greece, he decided to unite the world that was then known to him. and beyond
He thus embarked on a grand campaign that united Greece, Asia Minor, Egypt, creating a marvelous melting pot ("Hellenistic Times") and then some, continuing like a Cpt Kirk to uncharted territory, running out of steam and dying without ever returning home!
An epic of course. But what he left behind was a globalization of sorts (see my post "Globalisation, today and in 300 BC") that lasted for a while. But was not sustainable. Had he focused on uniting the 200+ Greek city states into a permanent entity, History could have been quite different (especially that of Rome).
Lessons for 2011 Europe?