Sweep of Stars by Maurice Broaddus

The Muungano empire strived and struggled to form a utopia when they split away from old earth.

Freeing themselves from the endless wars and oppression of their home planet in order to shape their own futures and create a far-reaching coalition of city-states that stretched from Earth and Mars to Titan.

With the wisdom of their ancestors, the leadership of their elders, the power and vision of their scientists and warriors they charted a course to a better future.

But the old powers could not allow them to thrive and have now set in motion new plots to destroy all that they've built. In the fire to come they will face down their greatest struggle yet.