U.S. Army. I served, it sucked. And if I knew then what I know now... The purpose of the U.S. Army is to kill foreigners that don't want to do what the tyrant living at 1600 Pennsylvania Avenue tells them to do. So he sends his mercenaries to kill them.
As I soldier, I got paid to obey orders. All military of all governments are MERCS!
Unpaid soldiers are NOT Mercs.