Council of Fire is both the first and second book in the Arcane America series. First because it is chronologically first but second because Uncharcted, written by Kevin Anderson and set in the same universe a few years later, came out a year earlier, so... it's a prequel, but it was written by a different author and from what little I know of Uncharted, there's not much in the way of character crossovers (if any). ANYWAY, the basic premise is that when Halley's Comet returned in 1759, it passed a little closer than expected and the Eastern hemisphere actually passed through the comet's tail. As a result, strange forces have awoken on Earth, and the Old World is either destroyed or completely separated from the New World by physical and supernatural barriers. As a result, the situation in the New World has suddenly become vastly more complex as the balance of power shifts dramatically as things of myth and legend suddenly become horrifyingly real and slaves and natives have the powers of magic at their disposal. The English and French colonies of the region as well as their native allies face stark choices about their future and the old enmities are suddenly far less important. In the midst of this difficult situation, the remnants of the English armed forces, who had thought themselves on the brink of defeating the French, are stretched thin trying to protect the frontier while also dealing with outbreaks of uncanny powers and facing supply shortages that the colonies are ill-equipped to support; moreover, there's the unpleasant issue of who exactly they report to when the King is gone and the only member of the Royal House in this hemisphere is Prince Edward, a young naval officer.
All in all, I found Council of Fire to be a pretty fun book, the story is interesting, the world is intriguing, and the colonial America setting is generally well-developed. It's not the most innovative concept as it reminded me of a kind of mash-up of Stirling's the Peshawar Lancers (though with the Eastern Hemisphere getting it instead of the Western Hemisphere), Butler's Witchy Eye series, Card's Seventh Son series, and Stackpole's Crown Colonies series, though it does enough to not feel like a ripoff. I did find it a bit disappointing that the colonials themselves are almost entirely secondary characters in this story as almost all the major characters are either French or English military officers, slaves, or Iroquois, and it seems like that's neglecting a huge aspect of the universe. In the book, the English military remnants basically dictate the political future of the colonies with no real consultation with the colonial leaders (of which, only New York's governor is given any real book-time and that as a problem), which seems rather a wasted opportunity to me since in our real timeline, the late 1750's/early 1760's were when the colonies first made fledgling efforts to actually work together and began to consider that they might not need Britain's oversight. Maybe it was a subplot that just didn't fit in the story. I don't know, admittedly, the colonies didn't really get angry at Britain (and, specifically, the Hannoverian Monarchy) until the post-French and Indian War Intolerable Acts, which obviously don't happen in this book.
All in all, if you enjoy Eric Flint's alternate history novels, then this may not be up to the standards of the best of the 1632 series, but it's quite enjoyable for what it is with a more fantastic take on the genre.