The Legacy Trilogy Series by Ian Douglas

In the future,earth's warriors haveconquered the heavens.But on a distant world,Humanity is in chains ...Many millennia ago, the human race was enslaved by the An -- a fearsome alien people whose cruel empire once spanned the galaxies, until they were defeated and consigned to oblivion. But a research mission to the planet Ishtar has made a terrifying -- and fatal -- discovery: the Ahanu, ancestors of the former masters, live on, far from the reach of Earth -- born weapons and technology .. moreIn the future,earth's warriors haveconquered the heavens.But on a distant world,Humanity is in chains ...Many millennia ago, the human race was enslaved by the An -- a fearsome alien people whose cruel empire once spanned the galaxies, until they were defeated and consigned to oblivion. But a research mission to the planet Ishtar has made a terrifying -- and fatal -- discovery: the Ahanu, ancestors of the former masters, live on, far from the reach of Earth -- born weapons and technology ... and tens of thousands of captive human souls still bow to their iron will. Now Earth's Interstellar Marine Expeditionary Unit must undertake a rescue operation as improbable as it is essential to humankind's future, embarking on a ten-year voyage to a hostile world to face an entrenched enemy driven by dreams of past glory and intent once more on domination. For those who, for countless generations, have known nothing but toil and subjugation must be granted, at all costs, the precious gift entitled to all of their star-traveling kind: freedom! less

When called to do battle many light years from home, the 1st Marine Interstellar Expeditionary Unit rose to the challenge -- and now thousands of enslaved humans have been freed from the alien yoke. But Earth is twenty-one years older than the home planet they originally left, and the Marines need time to retrain and readjust -- time they do not have, due to the bizzare disappearance of a detachment of their brothers- and sisters-in-arms... moreWhen called to do battle many light years from home, the 1st Marine Interstellar Expeditionary Unit rose to the challenge -- and now thousands of enslaved humans have been freed from the alien yoke. But Earth is twenty-one years older than the home planet they originally left, and the Marines need time to retrain and readjust -- time they do not have, due to the bizzare disappearance of a detachment of their brothers- and sisters-in-arms. It is a mystery, but there is a starting point: an ancient wormhole threading through the Sirius system. Whatever waits on the other side must be confronted, with stealth, with force, and without fear -- be it an ancient enemy or a devastating new threat.The Marines are heading into the perilous unknown . . . and what transpires there could reshape the universe for millennia to come. less

With the planet's fighting men and women deployed across the galaxy—battling in the noble cause of enslaved humanity—the insidious Xul have reached across space to devastate the unsuspecting Earth with asteroid fire. Without warning, a once majestic world is reduced to near-rubble—and the very future of humankind is in dire jeopardy.Interplanetary leaders are on the brink of abandoning Earth and its colonies to an overwhelming enemy... moreWith the planet's fighting men and women deployed across the galaxy—battling in the noble cause of enslaved humanity—the insidious Xul have reached across space to devastate the unsuspecting Earth with asteroid fire. Without warning, a once majestic world is reduced to near-rubble—and the very future of humankind is in dire jeopardy.Interplanetary leaders are on the brink of abandoning Earth and its colonies to an overwhelming enemy. But Brigadier General Garroway of the Marine Interstellar Expeditionary Unit is unwilling to concede defeat—not as long as there's a single marine willing to give his or her life in defense of their embattled homeworld. The ultimate battle is about to be waged—with breathtaking new attack technology, an ancient code of courage, and the help of an ally race that once inhabited the Earth—in a war that will alter the universe forever . . . less