Stark's War (Bk. 1)

The Americans were the first to set foot on the moon. They intend to be the last.
 
The United States of America reigns over Earth as the last surviving superpower. To build a society free of American influence, foreign countries have inhabited the Moon, taking advantage of the natural resources to earn their own riches. Now the U.S. military has been ordered to wrest control of Earth’s satellite from America’s rivals.
 
Sergeant Ethan Stark must train his squadron to fight against a desperate enemy in an airless atmosphere at one-sixth normal gravity. Ensuring his team’s survival means choosing which orders to obey--and which to ignore...