Interesting sociological theory

I would like to preface this post with a brief disclaimer, because people sometimes jump down my throat about this. I did not invent this theory, and I'm not saying I subscribe to it. I am simply saying it is an interesting idea, and pertinent to our discussion. That said...

I discovered this theory in a class on Anglo-Saxon literature and Tolkien (on top of being an IR freak, I am also a history and lit buff, so ignore the general geekiness to follow). It actually derives from an analysis of Anglo-Saxon history and literature, particularly Beowulf. There is a general underlying theme in
Beowulf in which warriors are both heroes and monsters. For example, Beowulf, the soldiers in Heorot Hall, and Grendel are all, at various points, referred to by the same kenning (kennings are different words that the Anglo-Saxons came up with to describe things, I suspect because they needed more alliteration in their poetry). Historians and English majors suspect that the point that the Beowulf author(s) is/are trying to make is that Beowulf is a hero so long as he uses his power against an enemy. He can become a monster if he turns his power inward against his own people. This is something that can be seen across Anglo-Saxon, and indeed, most of Germanic, society in the pre-Christian era. Kingdoms have to continually expand so that soldiers can take loot. Once a society ceases to grow, the warriors turn their violence inward, and shred the kingdom. For this reason, kings actually attempted to war with their neighbors. They were also known as "ring givers", because they won loyalty by giving loot to their earls. This is important because it initiated a sociological theory that war exists so as to turn the destructive forces of a people outward. Otherwise, there is internal chaos and collapse. This branches into an idea that people drawn to the military may be of a certain mindset, and will either kill foreigners, or commit crimes within the state (like I said, I don't necessarily agree with this). It's just an interesting way to look at whether we can ever end war, or at least the abuses inherent in it, because we will always need to orient destructive forces outwards.