The Ember War — Richard Fox

A dire warning. An impending alien invasion. Only one chance for survival.
In the near future, an alien probe arrives on Earth with a pivotal mission -- determine if humanity has what it takes to survive the impending invasion by a merciless armada.
The probe discovers Marc Ibarra, a young inventor, who holds the key to a daring gambit that could save a fraction of Earth's population. Humanity's only chance lies with Ibarra's ability to keep a terrible secret and engineer the planet down the narrow path to survival.
Earth will need a fleet. One with a hidden purpose. One strong enough to fight a battle against annihilation.
The Ember War is the first installment in an epic military sci-fi series. If you like A Hymn Before Battle by John Ringo and The Last Starship by Vaughn Heppner, then you'll love this explosive adventure with constant thrills and high stakes from cover to cover.