If there are no taxes period, then a nation would be hard pressed to exist as a cohesive unit, or at least the capacity to act as a cohesive unit easily.

Hey Blake! I highly recommend checking Bruce Benson's book out: https://www.amazon.com/Enterprise-Law-Justice-Without-State/dp/1598130447/ref=sr_1_1?ie=UTF8&qid=1471444202&sr=8-1&keywords=bruce+benson

If justice without the State is not only possible but preferable, which in my opinion is far more complicated than a military, then I think it is at least possible that defense could be secured the same way as well.

It's a very deep topic, and that's why instead of approaching the military head on, which may be a bit of an emotional hot spot, I think it may be useful to explore these concepts in relation to other important things the government does and then extrapolate out those ideas from those principles.

I have many friends in the military. I know that they are good people. I know that their hearts and intentions are 100% in the right place. People in the military aren't necessarily bad or being duped, rather most are trying their best to utilize their skills to help the world in a way that they think is the best that they can.

Either way, just know that even as an anarchist, I respect the shit out of you :)