Chapter 1, which originally stood alone as a short story before becoming the lead chapter in a novel with the same title, establishes a number of themes and motifs. Briefly, among the motifs are love and death, where love is equated with life through references to Martha; the death of Ted Lavender; Jimmy Cross's reaction to Lavender's death; lists of what the soldiers carried in their rucksacks.
A prominent motif is weight versus weightlessness. Martha is the primary vehicle for the weightlessness motif, although, after April 16th, Ted Lavender also contributes significantly to this motif of weightlessness and weight; he combines weightlessness as they remove the things he carried with dead weight as he lies "waiting" for the helicopter. O'Brien sets up a stark contrast between the psychological, emotional and physical weight of war that opposes the relative weightlessness of peace-time life that focuses on love and living:
walking barefoot along the Jersey shore, with Martha, carrying nothing. He would feel himself rising. Sun and waves and gentle winds, all love and lightness.
Briefly, among the themes are opposition of peace-time lives versus war-time lives. A corollary to this is the progression of the soldiers' old lives into the life of war. For instance: Cross carries the progress of his love for Martha; Lavender carries the progress of his need for tranquilizing medication; Dave Jensen carries the progress of his dental hygiene. Other themes are introspection that goes "far beyond the intransitive"; innocence that enters the war along with the soldiers ("just boom, then down - not like the movies..."); and personal identities that enter and determine experience in the war ("As a big man, therefore a machine gunner, Henry Dobbins carried the M-60"), for example, how Jimmy Cross's identity effects his experience of the war:
He loved her so much. On the march, through the hot days of early April, he carried the pebble in his mouth, turning it with his tongue, tasting sea salts and moisture. His mind wandered. He had difficulty keeping his attention on the war. On occasion he would yell at his men to spread out the column, to keep their eyes open, but then he would slip away into daydreams ....