Out of the Dark Series by David Weber, Chris Kennedy

The Galactic Hegemony has been around a long time, and it likes stability--the kind of stability that member species like the aggressive, carnivorous Shongairi tend to disturb. So when the Hegemony Survey Force encountered a world whose so-called "sentients" "humans," they called themselves—were almost as bad as the Shongairi themselves, it seemed reasonable to use the Shongairi to neutralize them before they could become a second threat to galactic peace... moreThe Galactic Hegemony has been around a long time, and it likes stability--the kind of stability that member species like the aggressive, carnivorous Shongairi tend to disturb. So when the Hegemony Survey Force encountered a world whose so-called "sentients" "humans," they called themselves—were almost as bad as the Shongairi themselves, it seemed reasonable to use the Shongairi to neutralize them before they could become a second threat to galactic peace. And if the Shongairi took a few knocks in the process, all the better. Now, Earth is conquered. The Shongairi have arrived in force, and humanity's cities lie in radioactive ruins. In mere minutes, more than half the human race has died. Master Sergeant Stephen Buchevsky, who thought he was being rotated home from his latest tour in Afghanistan, finds himself instead prowling the back country of the Balkans, dodging alien patrols and trying to organize scattered survivors without getting killed. And in the southeastern US, firearms instructor and former Marine Dave Dvorak finds himself at the center of a growing network of resistance putting his extended family at lethal risk, but what else can you do? On the face of it, Buchevsky's and Dvorak's chances look bleak, as do prospects for the rest of the surviving human race. But it may well be that Shongairi and the Hegemony alike have underestimated the inhabitants of that strange planet called Earth less

In New York Times-bestselling science fiction epic Out of the Dark, Earth beat back an alien invasion. Now we've got to make sure they don't come back, in Into the Light.The Shongairi conquered Earth. In mere minutes, half the human race died, and our cities lay in shattered ruins.But the Shongairi didn’t expect the survivors’ tenacity. And, crucially, they didn’t know that Earth harbored two species of intelligent, tool-using bipeds. One of them was us... moreIn New York Times-bestselling science fiction epic Out of the Dark, Earth beat back an alien invasion. Now we've got to make sure they don't come back, in Into the Light.The Shongairi conquered Earth. In mere minutes, half the human race died, and our cities lay in shattered ruins.But the Shongairi didn’t expect the survivors’ tenacity. And, crucially, they didn’t know that Earth harbored two species of intelligent, tool-using bipeds. One of them was us. The other, long-lived and lethal, was hiding in the mountains of eastern Europe, the subject of fantasy and legend. When they emerged and made alliance with humankind, the invading aliens didn’t stand a chance.Now Earth is once again ours. Aided by the advanced tech the aliens left behind, we’re rebuilding as fast as we can.Meanwhile, a select few of our blood-drinking immortals are on their way to the Shongairi homeworld, having commandeered one of the alien starships...the planet-busting kind. less