Traitors of Rome is the 18th and next-to-most recent (2019) title in Simon Scarrow’s Cato and Macro/Eagles series. It has dropped to $0.99 at Kindle and Kobo US today, Feb 2, 2021.
I’ve loved this series, starting with back when it was more of a historical mystery series set in a military setting, right up to now, when it seems to me more like a military/political historical series, with the dead bodies more related to the military/political goings-on than to classic mystery themes. But even though I’m mostly a mystery fan, I still love this series. And I have very fond memories of reading the early ones to my son, who was a huge military history buff from a young age, and being happy that I found a series we both liked!
Again $0.99 in the US. Links in the OP are still good.