Yesterday I finished Evil for Evil by K.J. Parker.

This is the second book in a trilogy.  I wrote about the first one here back in 2008.

This book continues directly after the first one ended, when one kingdom had fallen after defending a refugee from their more industrialized neighbour.  Some of the people, and the refugee, fled to a second neighbouring kingdom and this book continues the refugee's plan, whose details are not revealed until the end of the book, and develops some new characters around him, including the leader of the second kingdom.

It works pretty well, mostly focusing on the political and logistical efforts to find a way to defeat or avoid battle with the industrialized nation.  Like the first book in the series, it has some interesting descriptions of early technology, delving into mining, manufacturing and pottery making.