In William Gibson's play The Miracle Worker, Captain Arthur Keller is Helen Keller's father. He is also a retired Civil War officer, and his military career is a major element in determining what he wants and "what makes him tick."
Since the military requires complete, unquestioned obedience, Captain Keller requires this as well. His military career is one reason why he is so disheartened by his daughter's condition and even dumbfounded about how to handle her, how to teach her anything. In his mind, Kellers should be strong and obedient, and he is disheartened by the fact that his daughter, as he sees it, is neither of these things. As a result of being disheartened, Captain Keller has a tendency to treat the rest of his family coldly and even argues with his wife about what to do for Helen. We see his disheartenment in the first act when the stage directions describe "something like fury in [his face]" as he calls out Helen's name after realizing the fever has left her both blind and dumb. Again, in is mind, Helen is supposed to be healthy and obedient, and she is being neither; so, he is furious. More specifically, it can even be said that in not being healthy, she is being disobedient.
Another example can be seen in the first act when Captain Keller says he refuses to write to another doctor about Helen and refuses to let his wife write as well. However, Captain Keller's love for Helen is also a driving force, and he eventually capitulates. His letter eventually makes its way to the Perkins Institute for the Blind, where Annie Sullivan is hired as Helen's teacher.