Sub-Majer's Challenge - L. E. Modesitt

Alyiakal, a sub-majer in the Mirror Lancers of Cyador, The Empire of Light, is serving the last year of his tour as commanding officer of a remote border post. Rumors hint that the Cerlynese Duke, in retaliation for Alyiakal's success in a border skirmish, is readying an even larger attack.Against terrible odds, Alyiakal gains victory and a promotion. He takes leave only to discover his courtship of Saelora is opposed by her mother. Disappointed and reposted to the remote Pemedra Post— again—Alyiakal must navigate a rapidly developing war.In the midst of this, when forces outnumbering his command five to one attack a small town, Alyiakal is given orders to drive out the invaders, whatever the cost.