Marines

Erik Cain joined the marines to get off death row. The deal was simple; enlist to fight in space and he would be pardoned for all his crimes.
In the 23rd Century, assault troops go to war wearing AI-assisted, nuclear-powered armor, but it is still men and blood that win battles. From one brutal campaign to the next, Erik and his comrades fight an increasingly desperate war over the resource rich colony worlds that have become vital to the economies of Earth's exhausted and despotic Superpowers.
As Erik rises through the ranks he finally finds a home, first with the marines who fight at his side and later among the colonists - men and women who have dared to leave everything behind to build a new society on the frontier, one where the freedoms and rights lost long ago on Earth are preserved.
Amidst the blood and death and sacrifice, Erik begins to wonder. Is he fighting the right war? Who is the real enemy?