You can't help but feel a little sorry for Jimmy Cross. He's the leader of the platoon, but he's the opposite of the tough, Schwarzenegger or Sam Worthington-type you'd expect of an officer in Vietnam.
First of all, the guy daydreams all the time—sometimes about his love for Martha, a girl who'll never love him back, and sometimes about golf and its clear rules and expectations. Inevitably, though, during his daydreams, one of his men will get killed, and he'll blame himself for not being vigilant enough:
He had loved Martha more than his men, and as a consequence Lavender was now dead, and this was something he would have to carry like a stone in his stomach for the rest of the war. (The Things They Carried.42)
He signed up to be an officer on a whim, because his friends did. He's not comfortable being responsible for his men's lives, but instead of ignoring the responsibility, he confronts it head on… before he slips into another daydream, that is.