[karaterobot]

I read a ton of KJ Parker books last year, they were all really good. His most popular series is the one that starts with Sixteen Ways to Defend a Walled City. The premise is that a city is under siege by an army that has made it clear they're not going to spare anybody if they win. The protagonist is the highest-ranking surviving officer in the city, a lowly military engineer, who is suddenly in charge. Think The Martian meets The Siege of Gondor (or Constantinople). It's fantasy, but there's no magic.