Stark's War — John G. Hemry

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 their rivals. Sergeant Ethan Stark must train his squadron to fight in an airless atmosphere at one-sixth normal gravity against a desperate enemy. Ensuring his team's survival means choosing between which orders to obey -- and which to ignore...