The Genesis Fleet - Ascendant

"A young fleet officer and a Marine stand together to defend their colony in the continuation of the powerful Genesis Fleet saga.
In the three years since former fleet officer Rob Geary and former Marine Mele Darcy led improvised forces to repel attacks on the world of Glenlyon, Old Earth and the Old Colonies have continued to shrink their military forces.
But open warfare erupts once again when Glenlyon tries to force open a trade route. Isolated and alone, Glenlyon places its hope in informal agreements with other worlds also facing attack. But fiercely independent worlds settled by people who wanted to escape higher authority don't easily agree to such commitments. While politicians try to bring some kind of formal alliance into being, Geary and Darcy once again find themselves fighting desperately to defend their world, hoping they can hold out until help arrives.
If it comes at all..."