Necros Incident

The Necros Incident was the Time Lord designation for the event in which the Sixth Doctor confronted Davros on Necros, which they identified as taking place in the 47th century. (TV: Revelation of the Daleks, PROSE: Dalek Combat Training Manual)

Prelude
Davros, original creator of the Daleks, decided to turn on his creations, deeming them failures after they had lost their war with the Movellans. He unleashed the Movellans' virus on the Daleks which had rescued him in the hopes of him curing the virus. (TV: Resurrection of the Daleks)

After his attempt to exploit Lorraine Baynes' company was foiled by the interference of the Sixth Doctor, (AUDIO: Davros) Davros made his way to Necros. There he established himself in the Tranquil Repose as the "Great Healer", secretly exploiting the patients being kept in suspended animation by using them as subjects to be mutated into a new race of Daleks. (TV: Revelation of the Daleks)

Aftermath and legacy
Following his capture on Necros, Davros was transported to Skaro. One account held his trial was a trial of leadership, with him being granted command of the Daleks after a show of loyalty in exposing a Thal spy who had infiltrated his transport en route, revealing she had supplied him with a sample of the Movellan virus that he had chosen not to unleash. (AUDIO: The Davros Mission) Another had Davros being put on trial for his crimes before the Dalek Emperor, only to escape to Spiridon with the aid of the Sixth Doctor, who was playing his part in a scheme of his future self. On Spiridon Davros rediscovered an entombed Dalek army which he converted to his control. With this army he faced the forces sent by the Emperor to recapture him and invaded Skaro, claiming the title of Emperor for himself and instigating the Imperial-Renegade Dalek Civil War. (COMIC: Emperor of the Daleks) Davros' Daleks, known as the Imperial Dalek faction, matched the colour scheme of those he had originally created on Necros. (TV: Remembrance of the Daleks)

"The days of Davros and his humane work on Necros" were recalled by Seg of the Orcini New Daleks. (PROSE: War and Peace)

Behind the scenes
The Discontinuity Guide claims that Davros arrived on Necros 100 years following his rescue by the Daleks. It goes on to speculate that, whilst under interrogation during his incursion on Skaro, the Fourth Doctor had told Davros about the Human Factor Incident, which influenced him to convert humans into Daleks on Necros, Davros' conclusion being that, by possessing some of the Human Factor, the Daleks will not be slaves to logic and thus not be drawn into an impasse as they had with the Movellans.