How does Bruno's grandmother stand up for her personal beliefs against the Nazis?

On Christmas
Day, before Father became
Commandant of the concentration camp, he wore his new uniform for the
first
time.  The whole family applauded, and Bruno noticed that the soldiers seemed to show
his
father more respect when he wore it.  Grandfather was very proud of him
and told him he was
patriotic, but Grandmother told him that he was "Dressing
up like a puppet on a
string" (pg 90) Grandfather comes to his defense
telling him how proud he is of his son who
is helping to reclaim the
country's pride.  But Grandmother says, "...to see you in that
uniform makes
me want to tear the eyes from my head."  She stormed out of the house, and

Bruno didn't see much of his Grandmother after that, and she never forgave her son. 
When she
died, Bruno's mother said it was very hard on his father
because he never made amends with his
mother (pg 177)