This is the third in the 'Blood of Kings' series by K.M.Ashman. The setting is Wales in 1109, a country divided into a number of independent Welsh kingdoms and a substantial English presence. There is a truce between the English King Henry and the Welsh kingdoms, but revolts and unrest are commonplace.
A number of characters in the second book continue to play a role, most notably Prince Nesta who was married off to an English knight, and her brothers who organise different rebellions. The Welsh kings are torn between the realpolitik of protecting their kingdoms and moral support for rebellion.
The story appears to follow very broadly what we know of the period, which is not a great deal. It has small scale actions, rather than big battles - coupled with intrigue and treachery. The story is told well by an accomplished and fairly prolific author. I will keep reading this series.
For the wargamer this is definitely Lion Rampant territory. The rules fit this type of warfare really well.