I'm not gonna lie, this chapter threw me for a loop. It was remarkably philosophical, but at the same time barely made any sense. Just as I would start to catch on to what he was saying he would start talking in a completely different direction and I'd be lost again. He kept rambling about generalizing war and would follow these statements with conflicting (or antithetical, if you're feeling ambitious) thoughts. Perhaps him writing these accounts down is his own way of trying to make sense of his confusion. The war clearly affected him and changed him as a person, so I feel like writing this novel was more for himself than for his readers.
His repetitive nature was what reminded me of parallelism.
"War is hell, but that's not the half of it, because war is also mystery and terror and adventure and courage and discovery and holiness and pity and despair and longing and love. War is nasty; war is fun. War is thrilling; war is drudgery. War makes you a man; war makes you dead." (page 76)
Clearly, the second part is where the parallelism is in his description of war. It is entirely balanced. The first part was just an incredibly long run-on. All I'm saying is that O'Brien better watch out with sentences like that or he'll get an automatic D+ on a Roncalli writing assignment.