is anybody good at....

[ItalianStereotype]

military philosophy?

i am doing a midterm paper for my military history class (oh god, it is full of survivalists) and i really dont know a whole hell of a lot about it. i need to know why americans have always preferred the citizen soldier over the professional army, how this has fit into american political philosophy and protection of our liberty. it has to be a little more in depth than "because king george was bad." if you can give specific historic examples or book/online references that would be great too.