What is the main conflict in A Rumor of War by Philip Caputo?

Philip Caputo's memoir of life as a Marine during the Vietnam War is a three part story of war which illustrates a young man primed for adventure deployed in Da Nang and the stresses of a new kind of war, a disillusioned desk jockey documenting the staggering amounts of casualties, and finally a return to the field that results in burning villages and a trial for murder before honorable discharge. This stark visual of the Vietnam War is completed when Caputo returns as a field correspondent during the final moments of a long war.