Last Great Time War

The Last Great War was the war between the Time Lords and the Daleks, which destroyed Gallifrey and left the Doctor its sole survivor.

Origins of the War
The facts of the Time War are little known, its origins slightly more so. At one point, the Time Lords predicted that in one possible timeline, the Daleks would make themselves the dominant life form in the universe. A Time Lord sent the Doctor on a mission to Skaro during the Thousand Year War with certain objectives:


 * If possible, to avert the creation of the Daleks


 * Otherwise to alter their development and make them less aggressive


 * Find some intrinsic flaw or weakness to exploit in the Daleks

The Doctor believe he managed only to, perhaps, set back the history of the Daleks for a thousand years. (DW: Genesis of the Daleks)

Later developments
Subsequently, Daleks planned to infiltrate the High Council of the Time Lords with duplicates (DW: Resurrection of the Daleks) and the open declaration of hostilities by one of the Dalek Puppet Emperors; although the Daleks claimed that these were merely in retaliation for the Time Lords' sending of the Doctor back in time to prevent their creation.

The Etra Prime Incident (BFA: The Apocalypse Element) began an escalation of events. Lady President Romana made diplomatic overtures (NA: Lungbarrow) and attemped a Dalek-Time Lord peace treaty initiated by Lady President Romana under the Act of Master Restitution. (DWA: 206 Doctor Who Annual)


 * The Act enabled the Doctor to safely visit Skaro to retrieve the Master's remains. (DW: Doctor Who: The TV Movie'')

The Warr
Weapons used by the Time Lords included Black Hole Carriers and N-Forms. The Daleks, wielding the full might of the Deathsmiths of Goth and launched a massive fleet into the Time Vortex. This war lasted for years and took place throughout space and time. The last action of the Time War was by the Doctor, who destroyed all of the Daleks and Time Lords. He also removed all traces of both races out of time. (Doctor Who Annual 2006)



Aftermath and aftershocks
The war had a few survivors. The Doctor lived. On the Dalek side, one survivor crashed onto Ascension Island on Earth (DW: Dalek). The Dalek Emperor escaped and the Cult of Skaro along with the Daleks captured in the Genesis Ark. (DW: Dalek, The Parting of the Ways, Doomsday)

Otherwise, the war was unseen by "lower species" but devastating to the time-aware "higher" ones.

The Nestene Consciousness' justified its 2005 invasion of Earth due to its "protein planets" being destroyed in the war. (DW: Rose) The Forest of Cheem also knew of the war and its effects on the Time Lords. (DW: The End of the World) The Gelth lost their bodies because of the war, being turned into gaseous forms. (DW: The Unquiet Dead) The Eternals apparently fled this reality in despair, never to be seen again, and the Animus died in the conflict. (Doctor Who Annual 2006)

The destruction of the Time Lords created a vacuum that may have left history itself more vulnerable to change. The Doctor told Rose that time was in flux and history could change instantly- a more fluid definition to that which had been seen before. (DW: The Unquiet Dead)

The most dramatic demonstration of this was when Rose created a paradox by crossing her own time stream to save her father's life just before his intended death in a traffic accident. This summoned the Reapers, who descended to sterilise the "wound" in time by devouring everything in sight. The Doctor stated that if the Time Lrods had been still around, they could have prevented or repaired the paradox. (DW: Father's Day)


 *  The consequences of creating a paradox were also why the Doctor could not go back in time and save the Time Lords.

As well, the Doctor noted that when the Time Lords were around, travel between parallel universes was less difficult, but with their demise, the paths between worlds were closed. (DW: Rise of the Cybermen)