Starfire (The Guardian War Book 1). The Guardian War, #1

Thrust into a war on the other side of the Galaxy, the Alliance fleet led by legendary war hero Spartan faces an apocalyptical threat like no other. While the brutal conflict rages through the region, a dark and terrible threat emerges in the form of an armada spearheaded by a gigantic dreadnought called STARFIRE. This terrifying fleet leaves the galaxy in turmoil, and a string of devastated planets in its wake.
Spartan calls upon his allies including the renowned Syala, commander of the Black Widows mercenaries and a host of others to help him save their forces from inevitable destruction. As the STARFIRE armada approaches, entire planets begin their evacuation. But Spartan and Syala never back down from a fight. When others see danger and flee, they see opportunity, and they hatch a plan that that is as outlandish as it is impossible.
STARFIRE is the first book in a brand-new series in the style of Starship Troopers, Aliens and Battlestar Galactica, and set in the bestselling Star Crusades universe. A unique story that will take the reader to new worlds, and ancient foes never seen before.