Miliardo and Heero begin their battle. As they fight, they argue over the course of action taken by White Fang. Heero tells Miliardo that he'll be hated by Earth and resented by the colonies if he destroys Earth. Noin knows that Miliardo is planning to atone for the sin of destroying humanity by dying in battle in space.
Libra's engines start up. Lady Une orders that all mobile suits be destroyed, as Treize's orders. Sally, Howard, and Relena come into the control room. Lady Une greets Relena. Duo drops the scientists off on Peacemillion, and then joins the battle. Lady Une offers Relena the chance to take revenge for Darlian's death. Relena says it doesn't matter anymore. Howard assesses the situation. If both battleships collide with Earth, eternal winter will begin, and Earth will become inhabitable. The only way to avoid it is to change Libra's course. Duo is located near Peacemillion. Howard knows that the scientists are there as well.
Trowa disconnects the mobile dolls. He tells Dorothy that he has to keep living because he has a home to go back to. Dorothy has no place to go. Quatre asks Trowa to look after Dorothy, but Trowa knows she can take care of herself. He tells Dorothy to hurry off Libra, and she begins to cry. Duo realizes that the MDs have stopped moving. Trowa and Quatre get their gundams.
Lady Une asks Noin to relay the images of Heero and Miliardo's battle. She then broadcasts it to all of Earth and space, telling the citizens that the battle has no significance but is necessary to save humanity, the last battle.
The scientists try to start Peacemillion. Quinze finds them and shoots Dr. J. He accuses them of changing the orders to the gundam pilots, and with interfering with Operation Meteor to the very end. Professor G presses a button on the console, and as Quinze shoots again, Peacemillion's engines start, moving the two ships out of orbit.
Miliardo and Heero continue to fight. Libra begins to break up. Heero says that all of humanity is weak. A section of Libra breaks off and falls toward Earth. The colony delegation announces their desire to co-exist with the World Nation. The other gundams and the Maganac Corps hurry to destroy the chunk of Libra. Wufei comes through with Heero's buster rifle.
Heero and Miliardo fight within the last chunk of Libra. Heero cuts off Epyon's arm, but doesn't kill Miliardo. Quatre tells him to destroy the main power source. He's out of bullets and is about to self-detonate when Miliardo gets in the way. Miliardo tells Heero that he has the right to live, then destroys the main reactor himself. Heero tries to stop him, but Miliardo disappears in the explosion. Not all of the section disintegrates and continues into the atmosphere. Wufei gives Heero the buster rifle, and the other gundams and the Maganacs retreat so they don't get in Heero's way.
The chunk of Libra enters the atmosphere. Heero flies ahead of it, calling on the Zero system to guide him. He tries to aim at the chunk of Libra, but can't get a lock. The armor starts stripping off Wing ZERO as it flies through the atmosphere. Heero vows to survive through this. He gets a lock and fires. The piece of Libra is destroyed.
Everyone on MO-II cheers. Duo, Quatre, Trowa, Wufei and the Maganacs wait anxiously. Suddenly, Duo spots Heero flying out of the blast. Quatre realizes that Heero is the heart of outer space.
The pieces of Libra and Peacemillion fall to Earth as meteors. A new nation is formed, the Earth Sphere United Nation, that encompasses Earth and all the colonies. Peace has finally been achieved.
It is again Relena's birthday. She has become Vice Foreign Minister Darlian. She is leaving a colony in L1 to return to Earth with an important piece of legislation. As she boards the shuttle, a mechanic bumps into her. He apologizes briefly, then leaves. Relena is about to take her seat when she sees a teddy bear and a card waiting for her. She reads the card. She looks out the window, spotting the mechanic walking away from the shuttle. She shouts Heero's name, and he turns. Smiling, she tears the card in half, telling him to give it to her in person the next time. Heero smiles, turns, and walks away. Relena watches him leave with a smile on her face.