Donaldson, Scott. "Frederic Henry's Escape and the Pose of Passivity."
In
Bloom, Harold, ed. Ernest Hemingway's A Farewell to Arms.
New York:
Chelsea House, 1987: 97-112.
Frederic Henry feels guilty, says Donaldson, because he
survives the war and Catherine. At the beginning of the story, he does
seem sort of passive, and when he emerges from the Tagliamento River, he is a
more active person than even he lets on. "Thinking" becomes a code word
for having a sore conscience, but he really does plan his escape, though he gets
the barman, the opera singer, and even Catherine to suggest the parts of the
plan that he has already decided on, though he pretends with most that he is not
in trouble (98-103). Some of these observations are based on passages that
Hemingway cut from the novel, as well as those left in.
When Frederic tells us his story, knowing that he has deserted, he points out
repeated examples of soldiers who either did make a separate peace or suffered
so much from war weariness that they wish they could (103-104 ), and every
civilian he mentions after escaping seems willing to help him. He lets the
soldiers on the train think him a slacker, at least in part due to guilt (105)
[rather than cause a scene and be discovered a deserter]. Only sex
and liquor can help assuage his guilt for a while (106). Though he
sometimes avoids the war news, he also often seeks it out via newspapers (107).
Hemingway is not Frederic Henry; though he did fall for his nurse, Hemingway
actually deserved the silver medal that he got. Hemingway separates
himself from his narrator both in and out of the novel; outside of the novel, he
referred to Lt. Henry as "the inverted character." In the novel, we see
Lt. Henry's "lack of courage and competence" (109) and even his foolishness as
he shoots a sergeant for not helping with ambulances he himself has gotten mired
by leaving the main road and the retreat. Guilty Frederic also holds his
tongue when Ferguson accuses him of being a "snake" (111), though perhaps a
"fox" is more appropriate (112). Though Catherine tries to shield him from
the world and his own guilt, "it has not been enough" (112). "Hemingway's
untrustworthy narrator remains a principal agent of both his farewells--to war
as to love" (112).

I'm not sure I get Donaldson's point, or rather how much emphasis to place on
Frederic's guilt as a force that shapes his narrative. The supposed pose
of passivity that Donaldson sees would be self-serving and increase the
untrustworthiness of Frederic as a narrator of his own story.
Donaldson doesn't seem to emphasize irony as the effect of Frederic's love
affair. He finally becomes able to love someone and she dies trying vainly
to bear their son, who ought to be a symbol of their union, and instead becomes
a symbol of all those sons--9 million of them--who became casualties of the war.
On the positive side, Donaldson does provide some aspects of what makes
Frederic an unreliable narrator--his own guilt for what happened to his comrades
and to Catherine, though he ignores Frederic's grief and seems to discount his
bitterness. But Hemingway has Frederic administering anesthetic to
Catherine precisely to show that he shares in the culpability for her death--a
scene that Donaldson completely ignores.