Webb’s claims in the first two paragraphs quoted in the previous post remind me of this quote, provided by commenter Megamike:
“Beyond the Euphrates began for us the land of mirage and danger, the sands where one helplessly sank, and the roads which ended in nothing. The slightest reversal would have resulted in a jolt to our prestige giving rise to all kinds of catastrophe; the problem was not only to conquer but to conquer again and again, perpetually; our forces would be drained off in the attempt.”
The quote is from Hadrian, one of the last rulers before the beginning of the end of the Roman Empire, sometime between 117-138 A.D. Yet it evokes the now-faded Powell Doctrine of the late 20th century.
UPDATE: Link fixed.