Chapter XVII summarizes the routine that Lieutenant Henry and Catherine Barkley fall into after his operation. She volunteers for night duty so as to spend time with him, and he sleeps during the day. Catherine's friend Helen Ferguson speaks cynically about love and suggests that Henry encourage Catherine to take time off from working nights so as to get some rest herself.
This chapter, from which Catherine Barkley is mainly absent, is full nevertheless of ominous foreshadowing in the discussion between Lieutenant Henry and Helen Ferguson. Henry asks Nurse Ferguson if she'll attend his wedding to Catherine. Nurse Ferguson insists they will never be married; instead, she says, they'll "fight . . . . Fight or die." Crying, she continues, "But watch out you don't get her in trouble [that is, pregnant]. You get her in trouble and I'll kill you." Henry promises not to. Helen responds, "I don't want her with any of these war babies."
In this exchange, Hemingway draws a continuum, a straight line that runs from the kind of fighting that goes on between combatants in war, to sex and marriage, to fighting between couples (often referred to as the Battle of the Sexes), to childbirth, and back again. Though love and war seem to be exact opposites, the writer subtly suggests that they are, in fact, connected.
Also, Hemingway reiterates the theme of Henry's alienation from the Italian army by alluding to three other American soldiers staying in the hospital; one is there because he tried to dismantle an Austrian shell so as to take home a souvenir. The implication: the Americans involved on this front are dilettantes, neither truly serious about the cause nor entirely cognizant of war's consequences. Prior to receiving his wounds, this was certainly true of Henry himself.