The Millennium Giants, also called the Millennium Guard, awoke from thousands of years slumber to herald the new Batcon, or "Cycle of Ages," and cleanse the Earth of all its ills. From Egypt came the leviathan Sekhmet, From England arose Cerne, a Celtic giant with amazing destructive force. And from a volcano in the Yucatan peninsula came Cabracan, the "Mountain Destroyer" of Mayan legend. Strangely, these three behemoths awakened just as Superman was split into twin beings, Superman Red and Superman Blue, both fueled by the very same electromagnetic force that runs through the Earth's ley lines.
As if linked by magic, the Millennium Giants followed the ley lines, unleashing a catalog of natural disasters as they prepared the Earth for another thousand years' growth.
To halt the devastation caused by the Millennium Giants, the Supermen were joined by the members of the so-called Team Superman (Steel, Supergirl and Superboy), Aquaman, the Challengers of the Unknown, the Justice League, and the Teen Titans. When all hope seemed lost, the heroes finally realized that the Millennium Giants were part of the Earth's cycle of renewal. Superman Red and Superman Blue expended all their electromagnetic energies to cleanse the Earth's ley lines and finish the Giants' task without further destruction. The Millennium Giants then returned to their thousand year slumber to await the next Batcon.