The US Marine Corps has been a key part of the US presence in a host of combat zones in the first years of the 21st century, from Iraq to Afghanistan. With a front-line strength of over 200,000 active-duty personnel, the USMC is significantly larger than the entire armed forces of some countries. It fulfils a vital component of the United States' military capability, uniquely being able to deploy a combined-arms task force to almost anywhere across the globe in a matter of days. The infantry role is at the heart of USMC thinking; all Marines are trained as riflemen, and other components of...