An orc is an orc
Looking for comparable militarist societies, one things stands out: the entire orcish population is apparently armed. While other militarist societies may have an entire group, or gender, or age group, armed, there do not seem to be any in which the entire population is armed. Where are the women? I assumed, I admit, that all of the orcs in the film are male, and that the females are somewhere else. However, given the tremendous number of orcs seen in the Mines of Moria, the total population, if those were only the males, would be far greater than a subterranean/mountain habitat could support. So we have a society in which the entire population is armed. Such societies do not occur among humans, though they do among animals. Wolves, for example, are societies in which all adult members are armed and productive.
The orcs are not strictly hunters, since hunting/gathering could not support populations large enough to field large armies. Furthermore, the weapons carried by orcs tend to be highly ill-suited to hunting. Though they raid other societies for food (as in, the people of other societies) they cannot rely on that source, as some of their dwellings are too isolated (Moria, for example) or too large (Mordor) to allow raiding. We know they can eat bread, but that was most likely stolen, as in neither Mordor or Isengard is there any evidence of agriculture. Therefore, the orcs must have herds of some kind. The best evidence for this is the environmental degradation of Mordor. It is hard to kill an environment as totally as Mordor is devastated. So long as there are plants, the environment will regenerate. Trees can be cut down, brush burned, but it is hard to imagine someone plowing up all the grass for spite. One can imagine, as has happened in the Middle East, a lush country turned to desert by overgrazing. When you combine the impact of overgrazing with a dawning industrial revolution, one could achieve such devastation.
The orcish society, therefore, is a herding society with tendencies towards wolf pack behavior. The size of orc armies, however, indicates a level of social organization far above the clan level, but still maintaining the clans as a part of government. Thus, the orcs have a feudal society, but one in which weaponry is not limited to a noble class. Every orc is a potential noble, all he needs to be is the biggest, baddest, most violent orc in the clan. The orc noble is the alpha male (or female, as both genders serve as warriors). As the alpha male, the orc has two, conflicting interests: on the one hand, he needs to maintain his forces to defend his herds from other clans, thus he would want a large, well-equipped army, yet, on the other hand, he needs to make himself unchallengably superior to all of his subordinates. Thus an orc noble would create massive armies of poorly trained troops with which to overwhelm his enemies, and kill those orcs who begin gaining some skill at arms. And, given the lack of compunctions about cannibalism, all those extra troops serve as a reserve food source. That's why the orcs fight so often and so badly.
Which would he choose?