Theirs Not to Reason Why, book 1 : A Soldier's Duty
Jean Johnson2011

...What if you could see the future? What if you foresaw that, three hundred years from your time, your entire galaxy would be destroyed in an overwhelming invasion? What would you do to stop it, when it would all happen long after you were dead and gone?

These are the questions that Ia must face, and the obstacles she must overcome. Spurred by her teenaged visions of an apocalyptic future, the young heavyworlder woman seeks to set up a series of events, a domino-chain of actions and repercussions that will hopefully stop the coming invaders long after her time has passed. But in order to do so, she must enter the military and engage in a four-front war: an old, barely contained enemy whose twin goals of galactic conquest and lunch terrify all sane sentients; an ancient foe whose technology vastly outstrips anything the Alliance can fling at it; a fanatic, xenophobic religious movement on her homeworld which Ia dares not stop; and her ongoing battle against Time itself.

If Ia fails, the stars and planets of the Milky Way will cease to exist, and so will the countless lives that depend on them. But the odds of her winning the ultimate battle are very, very small, when even the slightest, most innocent-seeming misstep could domino down through time in the wrong way, and doom untold septillions of sentients to a dark and terrifying fall. Bound by the ice of her duty, burned by the fires of her conscience, driven by what she foresees, Ia must become the herald of death herself:

The soldier known as Bloody Mary.