After millennia of battle the surviving G'Gugvuntt and Vl'hurg realised what had actually happened, and joined forces to attack the Milky Way in retaliation. They crossed vast reaches of space in a journey lasting thousands of years before reaching their target where they attacked the first planet they encountered, Earth. Due to a terrible miscalculation of scale the entire battle fleet was swallowed by a small dog. The Hitchhiker's Guide to the Galaxy states that this sort of thing happens all the time.