Then there was a BIIIG battle and everyone went out in their mobile suits to fight. They fought and fought and fought. Athrun nearly killed himself but Cagalli saved him. In the meantime, Kira was fighting someone . . . Also, some Alliance ships (friends of Leia's) had arrived and were very helpful. And some aliens.
Author: Shirori Hitohana
While the aliens weren't expected, no one was really that surprised, as they had found the Whale Stone long ago. Han was very happy to have Chewey and his friend Lando Calrissan back; they were leading the ships. The three/four/five-ships alliance successfully destroyed Genesis, and the engines of most of the ships and mobile suits. With that and the introduction of a new war, against a bunch of aliens lead by something called a Sith, the people of the PLANTs and Earth were content enough to join up against a common enemy.
The Four/five-Ships Alliance that had been formed during the conflict proved crucial to maintaining diplomatic stability in the face of these new threats and the last stands of Blue Cosmos and Logos. The threat of the menacing Sith, especially the true Darth Vader, forced Logos to focus their propaganda upon them, or be vanquished. To be sure, there were many feelers extended between the two evil groups for possible alliances, but these feelers were quickly killed off by the Sith, leaving both sides with deep grudges. (Large portions of the membership of both Blue Cosmos and the Sith were particularly hesitant about such an alliance because of Blue Cosmos' and Logos' xenophobia.) Eventually, Logos and Blue Cosmos found themselves more and more marginalized, as Coordinators and Naturals fought together against Sith incursions, and traded with the Alliance (even the aliens) and repaired their vessels.
The war dragged on, but Earth was less emotionally scarred than it had been by the Bloody Valentine war, and focusing on fighting off Stormtrooper raids prevented a second Valentine war. Those who would've been heroes in that war became heroes in this new war. Shinn nearly became a Sith, but was barely won back by Athrun. Shinn's heretofore unknown Force potential made him the first known Earthling Force-user. He was unfit for padawan training, but managed to learn some discipline from his harrowing experiences.
Meanwhile, Leia, seeing the fighting potential of the Four Ships Alliance, had their vessels fitted with hyperdrives. Also, the mobile suits lent themselves to the Rebel Alliance's fighter wings and covert operations. Kira, Athrun, Cagalli, Duo, and the others all found themselves gainfully employed in daring raids. During the final destruction of the second Death Star, a daring two-front attack on the forest moon of Endor consisting of Ewoks and Rebel commandos, led by the Freedom, Justice, and Deathscythe, as well as Shinn's distinctive war whoop and orange lightsaber, resulted in far fewer Rebel, Ewok, and even Imperial casualties, as the battle was over very quickly.
In the resulting peace, Earth became a full member of the second Galactic Republic, maintaining all of its previous nations and national blocs (such as Orb and the Atlantic Federation.) Lacus became Earth's first Senator of the Republic, and she and Kira's first child was born at their second home on Coruscant, the Republic's capital. Meanwhile, Cagalli ruled as First Representative of Orb and married Athrun, and had children, and they were able to maintain fruitful scientific and commercial interchange with the nations of the Earth and the PLANTS, and the rest of the Republic, all of whom grew and prospered in the long peace.
(I knew Chihiro-sama wouldn't like it if I ended another story without marriages, hee!)