Why did the author show German soldiers, such as Hans Hubermann, performing civilian tasks instead of being shown on a battlefield? why did he focus on ordinary German civilians during wartime?

Hans is sent to Essen, where he is given an undesirable job with the Air Raid Special Unit: his unit must stay above ground during air raids to put out fires, prop up buildings, and save people. Everyone in the unit had done something impolitic to get this assignment. Hans tells them about his having given bread to a Jew; the Sergeant laughs and tells him he is lucky to be alive.

The job is smoky and incredibly dangerous. Occasionally people would roam through the haze and rubble seeking a missing loved one. In one shift, a bleeding old man asks Hans for help; Hans carries him to safety then finds the man is dead. Later, Hans trips over the corpse of a young boy while rushing from a building; a woman comes down the street asking if anyone has seen her son Rudolf, and the sergeant is unable to bring himself to tell her about the dead boy. The name makes Hans think about Rudy Steiner.

These ordinary, civilian tasks were assigned to men who'd insulted the Party and were specifically meant to set them apart in a negative way. This novel is intended to depict the ordinary man and the effects of the war on civilians..... not to examine battle or the soldiers who wages the war.