Robert Jordan is an American volunteer helping the Republican army in Spain. He blows up bridges and other structures, living a transient lifestyle as he goes where his orders send him. He is dedicated to the Republican cause and believes in ensuring its survival everywhere, but he is emotionally distant from the daily reality of the war for many Spaniards. Moving around so much, he does not allow himself deep emotional connections or relationships, and he is not usually around for the aftermath of his orders or their effects on families or towns that shelter him. He behaves logically and follows orders diligently.

Robert’s journey in the novel is toward learning to live in the present moment rather than putting everything off for after the war. His instant connection with Maria forces him to contend with his long-time assertion that he cannot have a romantic relationship while living amidst war. As many others discover in times of war, living for the moment can bring joy, even among sorrow. Robert displays further character growth in his memories of his father and grandfather, two opposites who represent heroism and cowardice to him. Robert briefly remembers his father when saying goodbye to Maria, suggesting a sort of closure or peace with his father.