What topics are explored or discussed in Chapter 1 of "The things they carried"

First Lieutenant Jimmy Cross carried letters from a girl named Martha, a junior at Mount Sebastian College in New Jersey. They were not love letters, but Lieutenant Cross was hoping, so he kept them folded in plastic at the bottom of his rucksack. In the late afternoon, after a day's march, he would dig his foxhole, wash his hands under a canteen, unwrap the letters, hold them with the tips of his fingers, and spend the last hour of light pretending. He would imagine romantic camping trips into the White Mountains in New Hampshire. He would sometimes taste the envelope flaps, knowing her tongue had been there. More than anything, he wanted Martha to love him as he loved her, but the letters were mostly chatty, elusive on the matter of love. She was a virgin, he was almost sure. She was an English major at Mount Sebastian, and she wrote beautifully about her professors and roommates and midterm exams, about her respect for Chaucer and her great affection for Virginia Woolf. She often quoted lines of poetry; she never mentioned the war, except to say, Jimmy, take care of yourself. The letters weighed 10 ounces. They were signed Love, Martha, but Lieutenant Cross understood that Love was only a way of signing and did not mean what he sometimes pretended it meant. At dusk, he would carefully return the letters to his rucksack. Slowly, a bit distracted, he would get up and move among his men, checking the perimeter, then at full dark he would return to his hole and watch the night and wonder if Martha was a virgin.