The irony of escapism
The memoirist reports escapism among the ranks of leadership. The chronic strain of warfare in East Asia, so far from their homes, the horror of modern warfare, it all adds up, and before long, there is a horrible habit among even the ranking officers to prioritize entertainment and distraction. Ironically, these exist to promote morale, but Lt. Caputo says it became so severe that eventually they would entertain themselves at times of true threat.
The irony of warfare
This memoir is predicated on an introduction that explores what Lt. Caputo remembers about his innocence, before he was made to experience warfare. The damage done in his psychology is done ironically, because he felt he would be a hero for going to war, but by the time the war was over, there was only confusion and misery for him and the other veterans.
The irony of war in Vietnam
The plain truth of the matter was that U.S. involvement in Vietnam had certain implicit problems, like the lack of public support. Ultimately, the irony reached a specific note (at least in this memoir) which is that with all the training in the world, no one could really expect to defeat the Vietnamese in Vietnam. They were dug in with trenches and tunnels by the time militaries arrived. The battle was one of chronic paranoia, because the Vietnamese had such a tremendous advantage due to terrain.
The irony of historicity
There is an ironic obstacle between the memoirist and his memoir, because to share his opinion is to tread lightly, because he intends not to discredit the USMC or the U.S. government, but the truth of Vietnam is impossible to share without exposing certain failures. He averts this criticism by explaining that his intentions are not historical, but rather experiential. The ironic difference between truth and historicity might remind a reader of The Things They Carried.
The irony of lived experience
To civilians back home or in the present, Vietnam represents one thing, but to veterans such as himself, Vietnam was a field for a whole litany of real human experiences which are so bizarre and horrifying that public opinion and conversation simply does not refer to the lived trauma of warfare. It doesn't even really come close.