Originally the empires of the Amstron and J'arrodic were allies. They created a wormhole, for which the access point was known as the Gate of Creation. Each sent astronauts to find out what was inside, but none returned. Only one transmission was ever received: "It's the face of the creator."
Over the years, each side disagreed about the meaning of the transmission, eventually believing the creator was like their own species and not the other. This lead to a war known as the Eternal Dogfight. They went to a planet, conducted an aerial battle, then moved on to another planet.
In 2015, the Dogfight came to Earth. By then, the war had been going on so long that few remembered why they were fighting. The Eleventh Doctor and his travelling companions discovered the origin of the combat, and Alice Obiefune volunteered to go through the Gate. Her grief over her mother's death immunised her from the extraordinary beauty which had captivated the previous astronauts. She returned through the Gate and told what she had found, thus ending the Eternal Dogfight. (COMIC: The Eternal Dogfight, The Infinite Astronaut)