In The Things They Carried explain the loyalty and the dependence of the men.
The short stories in this collection on the whole present the soldiers fighting together in the Vietnam War as recognising that their survival depends on how well they function together as a team. As a result, they are fiercely loyal of each other, and act in a way that clearly sacrifices their own desires and hopes for the good of the group of soldiers they are in. An example of this comes in "The Things They Carried," when Jimmy Cross daydreams about Martha, his supposed girlfriend, and as a result does not hear the silence that is an obvious indicator that something is just about to happen:
He was smiling. Vaguely, he was aware of how quiet the day was, the sullen paddies, yet he could not bring himself ot worry about matters of security. He was beyond that. He was just a kid at war, in love.
As a result, because of his daydream and his inability to act on the silence that he is but dimly aware of, one of his men is shot and dies. This indicates the extent of the soldiers' dependence on each other: they are in such a dangerous setting that they have to entrust their lives to each other, and when one of them does not do their duty or misses out on important points, as Jimmy Cross did, this could mean death for any one of them. Dependence and loyalty are natural conditions therefore of the situation that these soldiers are placed in.