Great Galactic War

The Great Galactic War, also known as the Republic―Yahg conflict, Yahg War, Parnack Conflict, and known to the yahg as the War of the Cosmic Imperative, was a brief, yet devastating, power struggle fought between the Interstellar Republic and the Yahg Empire which arose following the Cold War after the actions of several powerful individuals caused open warfare to break out.

Novels

 * Mass Effect: A Hero's Legacy