This book picks up right where the previous one left. In fact, the only reason to split this tale between two books I see was the length. There are three major plot-lines in here.
The first one is a defense by Union forces of its northern territory against an invasion by barbarians united by a ruthless and cunning leader. The Union has an advantage in numbers, but the majority of its soldiers are ill-equipped peasants who never wielded any weapons in their lives. The high command of Union consists of scheming politicians who do not care about the outcome of the war except to advance their own ambitions.
The second subplot is a defense by Union forces of its southern territory against an invasion of a mighty Empire united by a ruthless and cunning leader. Did you notice a similarity with the previous one? Everything I mentioned regarding north can be said about south as well.
The last subplot is a quest for an artifact by an extremely diverse group of people. This reminds of The Lord of the Rings somewhat, but the outcome of the quest is quite different.
Usually the middle book of the trilogy is the least exciting one of it. In this case the author cheated to avoid this: I already mentioned before that the first book feels like a giant prolog, so the second book is the place where things started getting interesting. Most of the characters are very memorable and feel like living people with seemingly bad guys showing traces of humanity and good guys developing their dark sides. The writing quality remains very good and for the most part the book does not disappoint.
I still find some kind of exciting is missing - I cannot even name it exactly and this is the reason for the book losing 1/2 of the star from perfect 5 star rating. Thus the final rating is 4.5 stars
This review is a copy/paste of my BookLikes one: http://gene.booklikes.com/post/875944/this-novel-does-not-suffer-from-the-middle-book-of-a-trilogy-syndrome