"What fresh worlds now remained for him to conquer?"
by cm

Alexander the Great
Creative Commons Attribution Share AlikeAlexander the Great - Credit: Yair Haklai
The quotation refers not to Wellington, but to Alexander the Great.  Popularly, the quotation is believed to be:

When Alexander saw the breadth of his domain, he wept for there were no more worlds to conquer.

But the original, from Plutarch's Moralia, was quite different:

When Alexander heard from Anaxarchus of the infinite number of worlds, he wept, and when his friends asked him what was the matter, he replied, "Is it not a matter for tears that, when the number of worlds is infinite, I have not conquered one?"