What is the main conflict in A Fire upon the Deep by Vernor Vinge?

A Fire upon the Deep by Vernor Vinge tells a tale of human scientists inadvertently releasing an ancient Blight on the universe, and the Blight racing an expedition to find what mystery has escaped their control: a secret that can make the Blight even more powerful or a Countermeasure that can once again defeat it. The world on which the starship carrying the mystery has landed has a medieval social order and dog-like sentient creatures are the dominant species. Two warring factions adopt human siblings who survive the landing, learning from them technology to bring about military victory.