- You may be looking for the eponymous comic story.
The Eternal Dogfight was a conflict between two vast galactic empires, the Amstrons of the Great Wheel and the J'arrodic Federation. It was a war so ancient that even the scholars of Gallifrey were unaware when it started. (COMIC: The Eternal Dogfight)
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. (COMIC: The Infinite Astronaut) This led to a war known as the Eternal Dogfight. The war was fought according to a precise legislature. Sometimes, the hostilities would occur near an inhabited solar system. In such cases, both galactic empires would send ambassadors to assure the locals that no harm is meant to them. However, tragic accidents could still happen. (COMIC: The Eternal Dogfight)
In 2015, the Dogfight was fought near Earth atmosphere. By then, the war had been going on for countless generations. (COMIC: The Eternal Dogfight) 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 Infinite Astronaut)