In the first series of the 2005 revival, writer Russell T Davies introduced the concept of the Time War to streamline the Doctor's backstory for new viewers of the show. It was a war across all of time and space which resulted in the destruction of his own people, the Time Lords, and their enemies, the Daleks, at the hands of the Doctor. The Doctor's remorse for his actions in his Ninth, Tenth and Eleventh incarnations is a key part of his characterisation throughout the revival. The Time War happened between the 1996 television movie and 2005 opening episode "Rose" according to the show's internal chronology, although the events of past serials such as "Genesis of the Daleks" have been retroactively attributed to the Time War. It was never shown on-screen until "The End of Time", which was both Davies' last story as head writer and producer and David Tennant's last regular story as the Tenth Doctor. This episode featured brief views of Gallifrey and the Time Lords on the last day of the Time War.