A recent book about the Persian Wars hit upon one of my many pet peeves with regard to discussing the ancient world. This book, which I thought was, for the most part, a fairly innocuous account of the wars between the Achaemenid kingdom and the Greek city states, had strengths and weaknesses, and I had bigger complaints about book as a whole, but one point that the author kept coming back to rubbed me the wrong way.
The author kept saying that the Achaemenid expansion (and, particularly, the invasion of Greece) was essentially a jihad or crusade—i.e. a religious imperative. He reaches this conclusion by looking at Persian propaganda that presents the king as the earthly representative of Ahura Mazda and the bringer of order to the lands inhabited by chaos. The Persian royal ideology mandated continual conquest and justified the kings’ place atop the social hierarchy, but does this royal ideology mean that there was a religious imperative for conquest that could be used to inspire followers? I think not.
To my mind, the biggest difference is that while the Persian kings crafted religion into an ideology that justified their imperialism and rule, it was, for the most part, not used to motivate soldiers. I qualify that statement mostly because an appeal to Ahura Mazda might have motivated the Persian contingents and commanding officers, but much of the Persian army in Xerxes’ invasion of Europe was not Persian and therefore it is improbable that the vision of the universe presented by Zoroastrianism would serve as a motivation for, say, Egyptians or Ethiopians. One need not totally believe that the soldiers were driven to battle by whip-wielding overseers to suggest that they religiously inspired.
In contrast, the Platonic ideal of a crusade (as it were) is a religious imperative, not just on the part of the leadership, but on the part of all followers, to wage a war of conquest for religious reasons. [This is true under one definition of jihad, too, but the issue is somewhat more complex.] Leadership can manipulate the impetus for conquest and benefit from it. Eventually religion will justify conquest if they are successful, but it is religious fervor that opens the door for conquest. In the Persian example, the step of using religious fervor for conquest is skipped.
Ultimately, the most damning fact with regard to the religious imperative of conquest is that the Persian kings gave up invasions of Greece after Xerxes’ invasion in 480. They continued to be involved in Greek politics to the extent that they can plausibly be said to have conquered Greece without an invasion, but the wars of expansion largely stopped and yet the dynasty continued to exist for another hundred and fifty years, seemingly satisfied to be a beacon of light for the territory they already possessed. There are mundane reasons for why the expansion was curtailed—dynastic infighting, rebellions, difficulties of managing such a large territory, etc—but one would expect at least one additional attempt at expansion if conquest of the entire world was a religious imperative the way this author presented it. What is left is a royal ideology that justified Persian rule as the representative of Ahura Mazda and thereby sanctioned conquest, which was not at all unusual, in the ancient world or otherwise. In fact, this sort of propaganda is hardly different than more recent justifications for invasions, bringing light to dark places in the world.