Dingiran

Description
The Dingiran are the descendants of Sumerians that were rescued from a planet-wide flood that affected Earth 10,000 years ago and were brought to a star system roughly 3,000 light years from Earth to its 4th planet that they named Dinguil.

History
Once members of the civilization of Mesopotamia on Earth, the planet was struck by a cataclysmic event, a massive planet-wide flood brought about by the arrival of the traveling water planet of Aquarius: the planet responsible for giving Earth it's water and the seeds for life over 6 billion years ago. When the floods came; the Sumerians were saved from destruction by an unknown race of alien beings that they have since revered as Gods, and were brought to Dinguil where they have lived for 10,000 years since.

Final Yamato
Aquarius emerged from space and arrived near Dinguil, the resulting gravitational pulls between the two worlds caused water to flow from Aquarius and travel towards Dinguil; where the water began to flood the entire planet. Almost immediately, the Dingiran fled aboard one of the planets continents that was re-purposed as a planetoid-vessel: Uruku, situated on it was the Dingiran Capital, and left the planet and thousands of their own kind to drown in the floods.

Almost at the same time, the Earth vessel Yamato had recently warped into the system and witnessed the floods ravaging Dinguil and set out to evacuate as many Dingirans as they could, only for a wave to crash into the side of the Yamato just as the rescue operation was almost complete, causing the lifeboat full of Dingirans and Human Officers alike to crash into the waves and subsequently drown. The Yamato was forced to depart from the surface with only a single survivor: a Dingiran boy.

Almost immediately, the Dingiran fleet attacks the Yamato as it was departing from the system, stating to themselves that all vessels in space are their enemies, leaving the ship to its fate after the relentless assault from their signature Hyper-Radiation Missiles before returning to Uruku as it stayed in near orbit to Aquarius. Inside of the capital temple, Emperor Lugal; the supreme leader of all Dingirans, decides to make Earth the new home for his people, by speeding up the orbital pattern of Aquarius so it'd make it to Earth faster by warping it to there. Lugal then orders his elder son Lugal De Zahl, the general of the Dingiran fleets, to confine all Humans to Earth so they would be destroyed in Aquarius' floods, allowing the Dingirans to move in after the waters had receded enough.

Lugal De Zahl would then engage his forces in confining the Humans to Earth by destroying every single Human colony and eventually destroying the shipyards on Earth; preventing anyone from Earth able to escape the oncoming floods of Aquarius coming in less than 20 days.

Yamato, being the only Earth Federation warpship not destroyed (having been sheltered in an underground shipyard on Earth just prior to the Dingiran assault), set out with a small fleet of 9 remaining Earth Federation warships to engage the Dingiran fleet orbiting near Pluto and stop the warping of Aquarius. They soon discover that the Dingiran boy had managed to stow away aboard the Yamato. As the fleet engaged the Dingirans, the forces retreated after losing several of their fighters while the Earth Federation lost three of their Destroyers that sacrificed themselves to protect the Yamato from the Dingirans' deadly Hyper-Radiation Missiles; an act that surprised the Dingiran Boy that he questioned why the Humans would do that, learning about the Human concept of self-sacrifice. As the Humans mounted a rescue for any survivors of the destroyers, Dingiran fighters emerged and fired upon the defenseless medical transports and officers before retreating again to the main ship in the Kuiper Belt as Yamato managed to fire upon them before their Missile Carriers could refuel again for another assault, leaving Lugal De Zahl surprised at this as his ship fled from the destruction back to Uruku.

Returning to Uruku, Lugal told his son about the genesis of their people and their divine right to Earth as the true Humanity, ordering for Lugal De Zahl to fight against the Yamato once again. His fleet managed to re-engage the Yamato over Aquarius and launch their Hyper-Radiation Missiles, only for the Yamato to activate a new weapons system designed to shoot down the incoming missiles before engaging the fleet and forcing Lugal De Zahl to retreat back to Uruku. Knowing that his son had failed him, Lugal activated the Neutrino Shield as Lugals' ship crashed into it and exploded, the Yamato however due to their Wave-Motion technology was able to bypass the shield and land upon Uruku to try and force them to surrender. A massive ground assault began between the Humans and Dingiran forces as Chief Combat Officer Kodai Susumu of Earth charged his way to get Emperor Lugal to surrender peacefully; attempting to appeal to his humanity as a species originating from the same world, only for Emperor Lugal to activate the warp one last time as Aquarius was now only days away from Earth before he turned his pistol on Kodai. The Dingiran Boy leapt into the path of the blast; revealing that he was Emperor Lugals' younger son and tried to get his father to stop this insanity, only to die as the Emperor walked away without looking back. Lugal activated the hidden fleet within Uruku that destroyed their city as he flew off with his strongest of warriors while the Yamato escaped on their own.

The Yamato performing a desperate gambit to stop Aquarius from flooding the Earth, loaded up with Heavy Water pumped from the Dingirans' absorption facility built on the planet to fuel the Dingiran Fleet with. Knowing of their plan to try detonating the Yamato at the mid-point between Aquarius and Earth to stop the flow of water from reaching Earth, Emperor Lugal sent himself and his entire fleet to destroy the Yamato, only for them to come under attack by Dessler and the Gamilas Fleet who came to help save the Earth. In the ensuing battle between the Dingirans and the Gamilas, Yamato escaped back to Earth while the entirety of the Dingiran fleet was wiped out, bringing a final end to Emperor Lugal and the extinction of the Dingiran species.