Mamelukes

Mamelukes is the fourth novel in Jerry Pournelle's Janissaries series. (Unfortunately, it is also his final novel.) When Jerry passed away, he left behind the nearly completed manuscript, and his son, Phillip Pournelle, took on the task of finishing it based on his father's notes. David Weber, a fan of the series, also came on board to help polish the story.
It is a damn good book, entirely consistent with Pournelle's earlier work in the series.
For more details about the book and how it was completed, I suggest listening to the three podcasts dedicated to it at the publisher Baen's website. (Episodes on May 29th, June 5th, and June 12th of 2020.)