system
Given the following post, respond as if you're commenting on Reddit:
human
[LOTR] What sort of infrastructure did Mordor have to feed and house a massive army with no obvious farmland or towns?
gpt
We only see the desolate plains surrounding Mt. Doom. In the book, Frodo and Sam wonder the exact same thing for the exact same reason:

*Frodo and Sam gazed out in mingled loathing and wonder on this hateful land. Between them and the smoking mountain, and about it north and south, all seemed ruinous and dead, a desert burned and choked. They wondered how the Lord of this realm maintained and fed his slaves and his armies. Yet armies he had.*

Fortunately, the narrator fills us in:

*Neither he nor Frodo knew anything of the great slave-worked fields away south in this wide realm, beyond the fumes of the Mountain by the dark sad waters of Lake Nurnen; nor of the great roads that ran away east and south to tributary lands, from which the soldiers of the Tower brought long wagon-trains of goods and booty and fresh slaves. Here in the northward regions were the mines and forges, and the musterings of long-planned war.*