Some of the following is repeated from my June 10 post.
"Friends never ask favors of their friendship. They ask favors of each other, making clear that their friendship is not at stake."
"As candidates for the perfect friendship, I picture two people who have emerged from a confessional, are kneeling side by side, and discover that they have been given the same penance."
"If you can appeal to my respect, my gratitude or a promise made, then do so. If not, then do not bother me with appeals to loyalty."
"Loyalty: allegiance asked when there are no grounds for asking it."
To be able to answer the question: "What is my duty?" -- is to have all one can ask of a parent's guidance and a teacher's wisdom.
In MacArthur's words "duty, honor, country", you have the complete canon and, importantly, the right sequence. Indeed, if you have acted from duty and honor, you have already fulfilled all obligations to country.
"Take no revenge that you have not pondered beneath a starry sky, or on a canyon overlook, or to the lapping of waves and the mewing of a distant gull."
~ Robert Brault