system
Given the following post, respond as if you're commenting on Reddit:
human
[LOTR/Hobbit] How does Sauron manage to maintain such a large army?

It seems to me that orcs always outnumber the human/elven/dwarven forces that try and stand up against them. How is this possible? Historical documents paint a bleak picture of Mordor being a dark barren wasteland. Nothing grows there, and yet the countryside is swarming with orcs. How are these hordes being fed? Where do they get materials for weapons?
gpt
The Sea of Nurnen is an inland large body of fresh water that had lands about it that were fertile enough to support agriculture.  Human slaves were used to work the farms around this sea in order to produce food to feed Sauron's armies.

Additionally, Mordor receives tributes from foreign human lands who serve Sauron, sometimes in the form of finished goods, materials and weapons, but also in the shape of food.

Finally, orcs are mutilates elves, so they reproduce after the manner of elves and men.  So they can feasibly reproduce all of their life, which is potentially forever.  Orcish women may be forced to live as eternal breeding partners while the males go off and fight.  Who the women breed with may be of little concern, so long as she continues to breed and produce more orclings.  It's a miserable existence, but the orcs have never had easy lives and their masters never seem to care.