Ok, I saw a thread below about someone who was trying to decide whether to join the Navy or Army.
This leads me to some other questions that I am curious about, who has the toughest/well trained combat unit in the U.S. military.
I know the Marines are tough, but are they really that much tougher/well trained than for example Army infantry? What about Army Special Forces?
Can an Army grunt later join the Marines/vice verca? What about in the Navy?