Just finished a book on Attila the Hun and the end of the Roman Empire. The author has pored through all the original sources and read a great deal between the lines, based on his extensive knowledge of the times. While the result is rather speculative in places (analyzing the intentions of Attila, for example), I am happy to trust the author’s speculations, because they are so well-informed.
I had never connected the dots showing that Attila’s actions were so directly responsible for the collapse of the Western Roman Empire. For example, the decisive battle of Adrianople, which crushed the army of the Eastern Empire, was fought by Goths, but they in turn had been forced into Roman lands by the depredations of the Huns. Attila himself never won a decisive battle against any Roman army; the battle of the Catalaunian Plains was a bloody stalemate from which everybody retreated, and the strategically brilliant invasion of Italy ended in an orderly retreat. The Gothic conquest of Italy was also triggered by upheavals in the Hun Empire following the death of Attila. And finally, all sorts of internal shenanigans and political intrigues that weakened the Romans were driven, to a large extent, by the need to respond to the continuing threat that Attila posed.
All in all, Attila emerges as a brilliant strategist who achieved wonders largely through the effective combination of diplomacy and the threat of military action—while seldom actually engaging in such action. When he did act, his campaigns were executed brilliantly, with a minimum of wasted resources and a maximum of benefits. Attila deliberately obliterated entire districts, not so much for booty as to demonstrate just how dangerous he was, thereby gaining considerable leverage in subsequent diplomatic negotiations. I suspect that he actually derived greater benefit from his diplomatic settlements than from his military campaigns.