The Siege of Echoherd. Dominion Earth: The Saurian Wars, #2

The fracture has begun. The cold war between the dynastic empires of sentient dinosaurs has turned hot, and the stakes have never been higher. In a stunning act of aggression, the Aquarion Clade, masters of naval power, launch a surprise attack on the peaceful Echoherd Coalition, silencing their sonic defenses and leaving them vulnerable. As war rages, the armored engineers of the Ankylar Bastion work to build a planetary shield, humanity's last hope against the coming celestial anomaly.
But the shield requires a rare mineral, found only in the territory of the ruthless, expansionist Shadowjaw Empire. The empires must now fight on two fronts-against each other and against the looming extinction.