The Guns of Empire (The Shadow Campaigns, Bk. 4)

After their shattering defeats at the hands of brilliant General Janus bet Vhalnich, the opposing powers have called all sides to the negotiating table in hopes of securing an end to the war. Queen Raesinia of Vordan is anxious to see the return of peace, but Janus insists that any peace with the implacable Sworn Church of Elysium is doomed to fail. For their Priests of the Black, there can be no truce with heretics and demons they seek to destroy, and the war is to the death.
 
Soldiers Marcus d'Ivoire and Winter Ihernglass find themselves caught between their general and their queen. Now, each must decide which leader truly commands their loyalty--and what price they might pay for final victory.
 
And in the depths of Elysium, a malign force is rising--and defeating it might mean making sacrifices beyond anything they have ever imagined.