I'm reading The Grand Strategy of the Byzantine Empire. I wouldn't recommend it if you're new to history, because it assumes a very high baseline of geographical and basic historical knowledge, and it can be dry at times. But if you've read some books on Rome before, and especially the Byzantine era of Eastern Rome, then the book is packed with gems on strategy, analyses of organization and logistics, culture, interesting stories and anecdotes, and the personalities behind the vast and epic clashes of the era.
This passage about Attila is insightful --
Deliberately mingling and confusing force and negotiations, Attila normally proposed peace talks as soon as he invaded. That too was a way of dividing his enemies, for in each case the war party in Constantinople or Ravenna was denied the clarity of an all-out war with no alternative.It was also part of his method to justify his demands with legal, or at least legalistic, arguments. [...] It hardly mattered if Attila's arguments had any legal merit. Even a thin veneer of plausability was quite enough because he was not trying to persuade a court of law, but instead wanted to divide the counsels of his opponents When facing Attila, the peace party always had a legalistic argument, however weak, to accept his demands.
It's commonly recognized that one of the reasons that Hannibal lost to Rome was that he was unable to get full support from the Carthaginian aristocracy to fully back him with men, materials, and money.
Attila was able to intentionally create this dynamic with his opponents. When a nation is unified in the face of total war, it deploys all its forces and people work on the same page. But Attila created semi-justified positions for accepting his terms and tried to get debates going about how much to mobilize against him, thus slowing down his opponents, leading to smaller mobilizations that were less well-equipped, and giving people an "easier out" to surrender and pay him off.
It's a fascinating book. It can be dry and difficult, and it's not recommended for people new to history. But if you've already read on the period at all, you'd probably incredibly enjoy it.