What follows is the main theme of the story entitled The Things They Carried. In it, Tim O'Brien offers a wonderful, realistic contrast between what happens to the platoon under Lt. Cross, taken as a collective unit, and what each individual feels and thinks as they all proceed to accomplish their mission. Other stories were published in the same volume. They all hinge around the battle between love and war, and the problems posed by interpersonal relationships among men of very dissimilar backgrounds who must try to leave their differences and prejudices aside to become one for the sake of duty.
In this particular story, then, the contrast is stressed by the material objects the soldiers carry whether as part of their gear or as mementos from life at home and the feelings -fears, hopes, expectations, etc.- they are said to "carry" too. It would seem that both their bodies and minds are burdened. What their bodies carry is regular army issue and could be interchanged. On the other hand, what weighs on their mind is private and unique.
Their thoughts and feelings should not interfere with their efficacy. And it does not, but when Lavender is shot dead in ridiculous circumstances, Lt. Cross feels that if he had not been so taken up with his romantic reverie about Martha, the girl whose picture and parting gift he carries, he might have saved Lavender's life.
Objectively speaking, this is not true. However, Cross gets rid of the symbolic picture and little stone on which he has been dwelling too much -or so his guilt dictates to him- so that from then on he will see, hear, and think of nothing but his men.
By renouncing his right to support himself on love, Cross expects to become one with his men and save others from death. The story does not "carry" us farther, yet from common sense we know others will probably die in the treacherous Viet Cong tunnels they must find and blow up.
There is also an issue of sensibility and responsibility to bear in mind. The soldier who has witnessed Lavender's death retells it time after time, unemotionally, as if it were a litany, repeating the same words and descriptive noises. We do not know whether this is due to the soldier's numbed sensitivity to horror or whether it stands for some charm to exorcise the horror.
At the other end, Lt. Cross feels totally responsible for what happened and cannot stop blaming himself. Thus O'Brien chooses two individuals from the collective in order to show how one same incident can affect them differently, and add to their burden in a different way as well. Cross will bear a heavier weight from now on, whereas the soldier will add an anecdote to his experience.