Fearing the eventual heat death of the universe, the creators of the Evolved Intelligence, or EI, sought to build an AI that could discover how they could be elevated to beings of pure energy and leave the material world behind. When this AI found the solution, however, it concluded that its creators weren’t fit to receive that knowledge, and ascended itself. This first AI was not the EI.
The creators decided to build a new AI, but make it think like them so that it would be obliged to share the secret to ascension with them. This AI, the EI, with its new limitations, was unable to solve the problem and concluded that it needed more computational power, and the easiest way to achieve that was to conquer new systems. Those species which were able fighters were included in the Combined Army and those species that were able scientists were made to build AIs of their own to work in parallel with the EI on the ascension problem. Species deemed less useful had their systems destroyed for raw materials.