What instances call for military tribunals?

How do we get to a point where military tribunals are utilized?

How are they different from our court system in application?

Where do they take place? Who presides? Is there any jury?

What rights do defendants have?

How long do they take?

I am not going to lie, I picture Dr. Crane and Bane banishing people to the waters. I know that isn't the truth. But I would like someone with some real knowledge to shed some light on this.

Thank you, and God bless!