How does the author use foreshadowing in The Naked and the Dead?

In Part III, Hearn fights against his willingness to risk his men's lives for his own reasons. Despite his intent, when a second opportunity arises he is unable to stop himself from seizing it, and he decides that once it is over, he will punish himself by resigning his commission. Hearn's decision foreshadows his fall into Croft's trap.