First Great Time War

The Black Sun War was a time war fought between the Gallifreyans (and later the early Time Lords) against the Order of the Black Sun, (COMIC: 4-D War) based thirty thousand years in Gallifrey's future. (COMIC: Star Death, 4-D War)

History
The first strike of the war, from the Time Lords' point of view, was when a Black Sun agent called Fenris the Hellbringer travelled back in time to attack and prevent Omega and Rassilon from turning the star Qqaba into a power source for their time experiments. The attempt did not succeed but did cause the apparent death of the stellar engineer Omega. (COMIC: Star Death)

After Fenris' ruined mind was retrieved from the Time Vortex, the Time Lords used the telepathic brainfeeler Viridian to probe Fenris' mind. After learning of the Order's name, the Order attacked, killing Viridian and Fenris, along with nine of the Castellan's strike force before any further information could be retrieved. Wardog also lost his arm. The Order's attack lasted only thirty seconds before they vanished. (COMIC: 4-D War)

The Time Lords did not know why the Black Sun, whom they had never encountered before the attack, should want to strike at them. They surmised it was for something they had yet to do. (COMIC: Star Death, 4-D War) Years later, at a diplomatic conference, the Black Sun Elder was murdered by the parahuman Millenium, who was one of the Special Executive hired by Gallifrey Gallifrey. Millenium was controlled by the Sontaran ambassador Brilox by using a psy-snare to wipe Millenium's mind as part of a plan to secure the uranium rights on Desrault for the Sontarans. Wardog then wiped Brilox' mind after he found the psy-snare on Millenium. This provided the motivation for the war's beginnings, as from the Order's point of view, Gallifrey were the ones who had struck first. (COMIC: Black Sun Rising)

Behind the scenes

 * The comic stories comprising the Black Sun arc were an early collaboration between writer Alan Moore and illustrator David Lloyd, who would go on to create the graphic novel.

Guerra do Sol Negro