The Legion Chronicles Trilogy

This series follows Marine Corps Sergeant William Tell Davis as he tries to protect Earth by creating a fighting force made up human expatriates, an alien supercomputer, and a Roswell alien. The Deserter: Sgt Davis discovers a plot to destroy Earth and creates a fighting force to defend his home planet The Revolution: General Davis leads a revolution against the corrupt alien intelligence that spreads slavery and tyranny throughout the galaxy The Return: The Legion is disbanded by cowardly politicians and the Planetary Republic is enslaved by a returning alien race, William Tell Davis must lead the resistance if Earth will ever be free.