The first book in the "Worlds at War" series, which was never expanded upon further in this edition of the game. This book takes the conflict from the other planets in the solar system back down to a post-apocalyptic Earth, with detailed entries for all four of the Tribes of Earth (the Sons of Rasputin, the Templars, the Lutheran Triad, and Crescentia). It also gives entries for the troops from the Megacorporations (Capitol, Bauhaus, Imperial, Mishima, and Cybertronic), the Brotherhood, and the Dark Legion that are to be found on Dark Eden. Also included are rules for taking Tribes of Earth units in corporate armies, and bringing corporate armies down to Earth.
Really, this book is meant to be used on its own, with the rules (but not the army lists) from the original Warzone rulebook. However rules for including the full factions found in the Warzone rulebook were included in Dark Eden.