It's the middle of the 16th century in Europe. Magic exists, but is regulated and restricted to Christian men. Then Thomas Lorenz, a curious nerd trying to solve an interesting magical-scientific problem, figured out how to store magic. He had in mind practical applications like lights without fire; others had...other applications in mind. Nobody understands where magical power comes from, why some have it and some don't -- it comes from the World Behind, they know, but what that is is a mystery.
Martin Luther's reformation has upended Christendom from within, and the expanding Ottoman empire threatens it from without. Thomas is summoned from his university by the emperor -- one of Thomas's students is now making magical weapons for the other side, and he'd better get to work on countering that. Not only that, but they seem to have developed a weapon that can strip mages of their power, an existential threat to mages beyond the broader threat.
Spells of War by Gary McGath tells this story from several points of view. We follow Thomas and his associates as they try to understand the threat and develop counter-measures. We follow Petros, the student, and his associates who are pressed into service to the sultan. We follow soldiers who are plunged into new ways of waging war. And we follow Thomas's wife, Frieda, who pursues her curiosity about the World Behind while Thomas is away, while also caring for their two young children.
Spells of War is the sequel to The Magic Battery but stands alone. The Magic Battery starts with Thomas's apprenticeship and follows his explorations into stored magic and the ire of the church it attracts. I read and enjoyed both.
Spells of War tells an interesting story with characters I cared about. In both books, the author made me care about, and understand the inner struggles of, people who are on the "other side" -- the inquisitor in the first book and Petros and his peers in the second. Spells of War shows the devastation that war causes on all involved. I don't want to say too much about the Frieda arc for fear of spoilers, but it's engaging and gives us a very different perspective.
The world of The Magic Battery and Spells of War holds together logically. There's magic but it's not "oh, we have magic so we can do anything!"; magic has limitations, both technical and societal, and 16th-century Europe is plausibly altered to make room for magic but is still 16th-century Europe. But you can't just add magic and expect nothing else to change, either; adding magic changes society, and these two books show that well.
The Magic Battery has a satisfying ending that raises broader questions. Spells of War has a satisfying ending that raises more questions. I don't think a third book is coming (or not soon, anyway), but there's room for side stories, and one is linked from the author's web site.
I was a beta reader for both books in exchange for free copies with no expectations of reviews.