The Ascent

It was only supposed to be a minor military expedition and Kenneth Phon was only supposed to be an observer. But when the ambitions of powerful men turn to betrayal and murder, the largest human war fleet ever assembled finds itself leaderless and lost, thousands of light-years deep in the territory of a hostile alien empire.

With the fleet surrounded and on the point of surrender, Kenneth Phon takes charge and leads them in their fight home through hundreds of enemy systems. The underachieving son of a wealthy shipbuilder, Ken must fight off more experienced commanders trying to undermine his authority and fractious mercenary ship captains who'd rather fight each other or turn pirate than cooperate.

If he fails, not only will the fleet be destroyed, but the defenseless Earth will be sterilized by aliens bent on revenge.

(Based on a true story.)