Shad Callister: 2 books

A fleet of humanoids from beyond known space came in blasting. But Earth is fighting back.  Young ace pilot Deckham Bannison is the tip of the spear, and humanity is depending on him. So why aren't they telling him everything he needs to know? Flying heavily-armed starships into combat...

Sergeant John Fletcher was a combat hacker in the Green Wars, causing havoc among the enemy's robots.  He thought he left that behind. Awakening on a hidden island, he realizes that not everyone considers the war over. Pushed this way and that by a god-like A.I. and her lethal...