The Crucible of Empire by Eric Flint and K. D. Wentworth

Humanity has been conquered by an alien race called the Jao. Once, they were nothing but slaves, some living lives of rebellion in the deep woods, until the Joa put a new lord in charge of the Earth. This leader, Aille, oversaw the Earth when it was attacked by a new foe called the Ekhat, a xenophobic race who will only allow itself and the races it crafted to serve it exist in the galaxy.

The Rao were once one of those servant races, but rebelled. Now, the Ekhat see them as just another annoyance to be destroyed. When faced by an attack of the Ekhat, humans and Jao joined together to fight, and thanks to human innovation and crude projectile weapons that the humans pulled off of their old battleships, which the Ekhat had no defenses against, prevailed against the alien ships which most considered unstoppable.

It's rather obvious that the humans and Jao alone cannot prevail against the Ekhat, so the Jao and humans have joined into an association, or group, like each Jao homeworld has, called ava Terra. This shocks many of the Jao, who think of the humans as little more than dumb labor. Jao as a whole do not value innovation or creativity, seeing it as something that children alone do. But human creativity is the reason that the Jao and humans prevailed over the Ekhat.

Now, the ava Terra association have constructed a new ship, much larger than any ship ever constructed before, either by the standards of the Jao or the humans, and are sending it out into the galaxy to find new races to ally with against the Ekhat. This ship, the Lexington is carrying a complement of humans and Jao, some of whom are from a foreign association unused to working with humans, or dealing with human creativity.

And, on a world far from both Earth and the Jao, the Lleix cower on the single remaining planet of their Empire. Once, their civilization spanned seventeen worlds, but the attacks of the Ekhat have driven them to a single metal-poor world where life is a tremendous struggle. Their culture consists of various groups known as elian, each one like a guild, responsible for a single area of study. But their race is dying, and they don't have enough metal to build enough spaceships to save everyone and move on to a new planet.

At a meeting of the heads of the elian, one of the youngest members of the Starsifters, who are responsible for evaluating the debris from a recent space battle that happened in their system. Most of it is Ekhat, but this Starsifter, Jihan, insists that there is another kind of debris as well, belonging to a race once known as the Jao.

Though the Jao once served the Ekhat, and were responsible for the death of most of the Lleix, Jihan thinks it is possible that the Jao have rebelled against the Ekhat and now fight them. She thinks they should study the Jao and form an elian to do so.

Because speaking out against the head of the house is so frowned upon, Jihan is censured by the head of the house. But she finds support from a most unexpected place, the head of the Ekhatlore elian, Alln, who supports her founding an elian of her own, Jaolore. Gifting her with a member of his own elian, a youth named Kajin, who is horrified to be thrust from his own elian, Jihan and Kajin desperately research the Jao, in order to be ready when and if the Jao return to their system.

Back on Earth, the Lexington finally lifts, though not without a great deal of friction from the Jao from Krant, a fairly poor Jao homeworld whose ships were the ones who encountered the Ekhat in the Lleix system. Caitlin Kralik, Aille's servant, and daughter of the former President of Earth, is along for the journey, pouring over the Jao's records as well. And in it she finds a possible Ally, the Lleix- provided they were not completely exterminated by the Jao.

But when they finally warp into the Lleix system, the Ekhat have gotten there ahead of them, with five ships. Can the Lexington, as huge and powerful as it is, survive combat with five Ekhat ships, an unheard of number for a single ship to survive? And how will the Lleix, who already don't trust the Jao for the near-genocide of their race, react when they find out that the humans are the slaves of the Jao, not the other way around? Will the Lleix be able to trust the humans and the Jao to rescue them, or will the Lleix insistence on leaving behind 90% of their race- simply because they are unchosen by any elian sour the humans on the deal?

I picked this up, thinking it was the first book in a series, but it actually wasn't-it was the second book. The first one presumably told about how the humans assisted their Jao overlords to overocme the Ekhat. But even so, after some initial confusion and the (re)introduction of characters I'd never met before, I found myself figuring out quite easily what had gone before, and absorbing information about what was to come.

There are a few concerns if you are reading this book without reading the one that came before. It's never actually described what the Jao look like. My first impression was rather dog-like or cat-like, with ears and body postures used to convey all sorts of emotional information with each other. It's rather like adding emoticons to internet speaking, because apparently, the Jao are fairly stonefaced, with a lack of easily readable facial expressions because of their anatomy. And even though humans don't have the same problem, the Jao cannot read human expressions, either, and thus, humans have to mimic the same sort of body postures as the Jao. It must be very movement-intensive, given that one of the human characters refers to it as "dancing". But again, without a real description, readers can't know.

The Lleix are well-described, and we get a lot of information about their race as well. They tend to be tall and silver-skinned, with a kind of aureole around their head that seems like hair, but acts like flower petals, and are also described that way. They also seem a little bigoted, being that the reason why they take people into their elians is for reasons of beauty- if you aren't beautiful enough, no one will take you, which seems stupid.

The Ekhat are pleasingly alien, and make wonderful villains. Their race takes xenophobia and selfishness to the extreme, and the battles against them are described very well. The back of the book gives us more information on them, so I am assuming that they are going to be given a larger role in the next book, rather than it just being the authors showing off how much work they did on the Ekhat.

I enjoyed this book, and I found it very good to read. For those who haven't dipped into this series before, you may find the backstory and characters confusing at first, but by sticking with it, you'll find an interesting, gripping story of war in space against a xenophobic race who wants nothing less than to exterminate any race that is not itself. Highly recommended.