What is the particular value of having a World War II narrative told from the perspective of a German soldier?

Sajer frequently points out, and has it pointed out to him, that he is a Frenchman in a German uniform. How does his background shape his identity within the army? How does that sense of himself change over time as he gains more experience as a soldier fighting for Germany?

What purpose does the character of Hals serve throughout the book? Why does Sajer feel a particular kinship with him, and how does their relationship affect Sajer’s own development as a protagonist?