The Thousand Names

Set in an alternate nineteenth century, muskets and magic are weapons to be feared in the first "spectacular epic" (Fantasy Book Critic) in Django Wexler's Shadow Campaigns series.
Captain Marcus d'Ivoire, commander of one of the Vordanai empire's colonial garrisons, was serving out his days in a sleepy, remote outpost-until a rebellion left him in charge of a demoralized force clinging to a small fortress at the edge of the desert.
To flee from her past, Winter Ihernglass masqueraded as a man and enlisted as a ranker in the Vordanai Colonials, hoping only to avoid notice. But when chance sees her promoted to command, she must lead her men into battle against impossible odds.
Their fate depends on Colonel Janus bet Vhalnich. Under his command, Marcus and Winter feel the tide turning and their allegiance being tested. For Janus's ambitions extend beyond the battlefield and into the realm of the supernatural-a realm with the power to reshape the known world and change the lives of everyone in its path.