|Information in this article is non-canon|
It involved the Combined Herd, now joining together again after Gallim divided them, the Combined Pack, a cross-specis pack of Sharpteeth led by Chomper and his mate Andromeda, Strut and a few nice Egg Stealers, Ruby and her Fast Runner alllies, Swimmer Valley and Flyer Valley, Yellow Belllies, and Bron's and Ali's herds as the good side.
The enemy was led by the Bothteeth and Gallim, the Terror of the Mysterious Beyond himself. The Sharptooth enemy was led by Red Claw and included a large portion of the Valley of Sharpteeth. Sierra led the evl Flyers and Ozzy led an army of Egg Stealers.
Things were quite nasty, with many deaths on both sides. Eventually, the main battle continued out into the Mysterious Beyond in the predawn hours. The final fight took place in the Mountains that Burn.
Chomper challenged Red Claw for control of the Valley of Sharpteeth. Petrie and Perrin fought Rinkus and Sierra, with Pterano coming to his nephew's aid. Ozzy and Strut fought. Littlefoot and Ali fought the Terror of the Mysterious Beyond, Gallim, himself.
Soon, Odul, Ela, Finley, and Liz were killed in the fight. Thud defected to Chomper's side and killed Fast Biter Leader. Screech was killed by Andromeda and Rinkus was eventually by Andromeda right before he would have killed Perrin.
Chomper looked like he was beaten, but was able to climb up a hidden edge of a cliff and pull down Red Claw to his death, while he himself was able to use his enemy as a ladder to pull himself back up to safey.
Strut eventually defeated Ozzy usuing a geyser that sent Ozzy into sharp rocks.
Sierra was going to kill Petrie, but Pterano intervened. Sierra eventually was killed by Pterano and it looked like Pterano was lost too, though he ultimately survived.
Gallim wounded Ali and was going to kill her, saying Littlefoot would lose her like he lost his mother. Littlefoot and Gallim battled at the top of the highest volanoe. The fight was intense, and there was an earthshake going on, in additon to major lava floor.
It eventually looked like Littlefoot was going to lose. However, his mother's spirit told him to use the Longneck tail whip, which he did, saving both his life and Ali's and sending Gallim to his death in the lava.
The heroes were all able to get out of the Mountains that Burn before many volcanoes erupted, killing Gallim's Domehead allies.
Chomper came to the Great Valley, now the leader of the pack, and ordered them all to stop. Bound by loyalty to the pack leader, they obeyed. The Great Valley War was over. The Bothteeth, minus the Fast Runners and a few others, were expelled forever from the Great Valley as were many of the Egg Stealers.
Chomper and his mate were allowed to live in the Great Valley for life as a reward for thier loyalty to the Great Valley and the two hunted evil Bothteeth and Egg Stealers and so the Leaf Eaters of the Great Valley didn't have to worry about being eaten by them. Litttlefoot was unbanished and made the new leader of Ali's herd. He and his new wife Ali took leadership of that herd, which they ran very effectively.