That sequel is 1634: The Baltic War, which I also co-authored with David Weber. So, I suppose you’d do well to read them back to back. That’s because 1633 has a sequel which is so closely tied to it that the two volumes almost constitute one single huge novel. That said, if I’m pinned against the wall and threatened with bodily harm, I’d recommend that you read Ring of Fire before you read 1633. It really doesn’t matter that much which of these two volumes you read first, so long as you read them both before proceeding onward. Thereafter, you should read either the anthology titled Ring of Fire or the novel 1633, which I co-authored with David Weber. That is the foundation novel for the entire series and the only one whose place in the sequence is definitely fixed. The first book in the series, obviously, is 1632. However, that would be a bit churlish-and when it comes down to it, authors depend upon the goodwill of their readers. What’s the right order for studying the Thirty Years War? If you find it, apply that same method to the 1632 series.” Whenever someone asks me “what’s the right order?” for reading the 1632 series, I’m always tempted to respond: “I have no idea.
Recommended Reading Order for the 1632 Series (aka the Ring of Fire series) By Eric Flint, November 1, 2020