Sword and Fire — Thomas S. Gressman

AN AWESOME MISSION
...has been assigned to Task Force Serpent: to destroy Huntress, homeworld of Clan Smoke Jaguar, the Inner Sphere's greatest menace. But the invasion has suffered a serious blow: Marshal Morgan Hasek-Davion has been struck down by an unknown assassin. With the fate of the entire Inner Sphere in jeopardy, only one other daredevil warrior is brave--and reckless--enough to bring the enemy to its knees....

She is General Ariana Winston of the famed Eridani Light Horse mercenary brigade, and new commander of Task Force Serpent. The battle ahead is dangerous and uncertain, but Winston and her courageous comrades have the upper hand with hard-earned battle skills honed to fighting-edge perfection--and a secret weapon that could destroy Huntress for all time....