Its been a banner decade for modern military fighting. In 2010 alone there were more than 70 armed conflicts across the globe from Sangin to Ingushetia.

As different as each of them were, they all had one thing in common, at some point one side wanted more troops.

Most battles eventually come down to boots on the ground and rifles in the field. So when commanders are building their ranks it's often with professional soldiers who know how to fight, and get paid well to do it.

The idea of a mercenary may seem a bit quaint in the 21st century, but those forces make a difference and are often all that stands between a leader and his fate.