Why does grandmother call father a puppet on a string?

In
chapter 8, Bruno recalls the last Christmas celebration he spent with his grandparents. During
the family gathering, Bruno's grandmother expresses her displeasure with her son's promotion in
the Nazi Party. Bruno's grandmother is unimpressed by her son's new Nazi uniform and calls him a
puppet on a string. Grandmother calls her son a puppet because he is casually carrying out
horrific orders handed down to him by his superiors in the Nazi government. Grandmother believes
that the Nazi regime represents and practices intolerance, violence, and oppression. She is
aware of the Nazi atrocities and feels like she has raised Ralf better than that. Bruno's
grandmother believes that her son is mindlessly following orders, like a puppet, without
exercising his better judgment. Despite the fact that Ralf knows right from wrong, he acts upon
the violent orders without hesitating. Bruno's grandmother causes such a disturbance that she
ruins the Christmas celebration, and Bruno and Gretel are sent to their rooms while the heated
argument continues.