Planetary Relocation Incident

The 2009 Dalek invasion of Earth was a war fought between the New Dalek Empire and other races - mostly Humans - in the Medusa Cascade. It was fought in the Medusa Cascade in a pocket dimension that was put one second out of sync with the rest of the Universe, in 2009.

Background
During the first year of the Last Great Time War, Davros's command ship flew into the jaws of the Nightmare Child at the Gates of Elysium. Davros, however, was rescued by Dalek Caan. Caan was the last surviving member of the Cult of Skaro, which had been destroyed during the events of Evolution of the Daleks post-Time War in 1930. After activating an emergency temporal shift, Caan managed to enter the timelocked Time War and rescue his creator, losing his mind and gaining psychic abilities in the process of flying "into the wind and flame". (DW: The Stolen Earth)

Davros made Caan his prophet, and set to work reviving the Dalek Empire of before the Time War. After building the Crucible, restoring the Dalek Fleet to 200 ships, and creating thousands of Daleks with the Kaled mutants inside grown from the cells of his own body, Davros set to work with creating a Reality Bomb. This superweapon was to destroy all of reality in every universe (except the Crucible), leaving Daleks as the only species in existence. (DW: Journey's End)

To power the Reality Bomb, 26 planets and one moon were stolen from various times and places across the universe so that their gravitational fields, once aligned, could act as a gigantic engine. These included Earth, which brought the problem to the Doctor's attention. The Shadow Proclamation, after the Doctor's visit to them, wanted to go to war with the unknown (to them) perpetrators of this event. However, the Doctor did not wish for a full-scale war, and left for the Medusa Cascade itself.

Invasion of Earth
Not long after the planets were brought into the Cascade, the Dalek Fleet attacked. Most of the efforts seemed to go to Earth. The Unified Intelligence Taskforce and the other armies of Earth fought back, but were no match for the Dalek onslaught and were quickly slaughtered. The "Valiant" was destroyed nearly immediately, the British Prime Minister Aubrey Fairchild was killed, the RAF retreated over North Africa and military bases across the planet were attacked and personnel exterminated, although Martha Jones successfully used Project Indigo to teleport away with the Osterhagen Key.

Other worlds out of the 27 were inhabited, and would have presumably put up a resistance, although these invasions were not shown.

A subwave network, made by the Mr Copper Foundation and used by Harriet Jones, former British Prime Minister, was used in an attempt to contact the Doctor. While the Daleks attacked Harriet's house, killing her, and then attacked Torchwood Three, Harriet, Torchwood, Martha and Sarah Jane Smith (with the help of Mr Smith) transmitted a message to the Doctor, helping him to find the location of the stolen Earth. (DW: The Stolen Earth)

The Doctor found the stolen Earth and arrived, while meanwhile the Dalek assault continued. Thanks to a time lock in the Torchwood Hub, the Torchwood team survived the Dalek attack. Sarah Jane, trying to find the Doctor, was found by Daleks but saved by dimension-hopping Mickey Smith and Jackie Tyler, who then surrendered to the Daleks to find the Doctor, who had been taken prisoner along with, Donna Noble, Jack Harkness and Rose Tyler and taken to the "Crucible". (DW: Journey's End)

Reality Bomb
The Daleks, using Davros' plans, created a weapon known as the Reality bomb which would destroy everything, even parallel universes. This weapon was powered by the 27 planets the Daleks had stolen, which included Earth. The Daleks had stolen these planets so that together they could power it. The Daleks ran a test of the bomb concentrated on a small group of human prisoners, including Sarah Jane Smith, Mickey Smith and Jackie Tyler. Mickey and Sarah Jane managed to escape to a side chamber and Jackie managed to teleport to it with her Dimension Jump once it recharged just before the weapon was tested.

This protected them from being reduced to atoms. This terrible weapon would wipe out all life in every universe. In Pete's World (which the Doctor said is further ahead in time than our world) the stars had already gone out due to the Reality Bomb destroying them. Meanwhile the Daleks captured and tried to destroy the TARDIS with Donna Noble still inside. They would have succeeded if not for the regenerative energy in the Doctor's severed hand triggering a Meta-Crisis in conjunction with Donna Noble in which a new version of the Tenth Doctor was produced. This new Meta-Crisis Doctor and Donna escaped in the TARDIS (which the Daleks and everyone else thought destroyed) and prepared to turn the Reality Bomb on the Daleks themselves.

Sarah Jane, Mickey, Jackie and Captain Jack threatened to detonate a warp star which would destroy the Crucible if the Daleks did not back down, and Martha Jones threatened to destroy the Earth with the Osterhagen Project (to make the required 27 planets 26) if the same thing wasn't done, but the Daleks teleported them all to the Vault and trapped them there with the Doctor and Rose. The Meta-Crisis Doctor and Donna then arrived in the TARDIS to put their own plan into action but were quickly foiled by Davros, who zapped them with his electricity-shooting prosthetic hand.

For a moment all seemed lost, however the electric shock that Donna had received caused her Time Lord side to activate. She had been part-Time Lord when the Meta-Crisis Doctor was created, causing her to gain the Doctor's intelligence. She manually deactivated the Reality Bomb, disabled the the Daleks and released the others by using some controls with the "gut instinct" of a human and the intelligence of a Time Lord.

Destruction of the Crucible
With the Reality Bomb disabled and Dalek controls malfunctioning, the Doctor's companions got rid of all of the nearby Daleks and Mickey held off Davros with Rose's gun. The two Doctors and Donna started returning all 27 planets to where they belonged, but the Supreme Dalek descended to the Vault and attacked, disabling the machinery before Jack managed to kill him. All of the planets but Earth had been returned, but the Doctor made preparations to use the TARDIS to tow it back. The Doctors also realised that Dalek Caan had been manipulating everything to lead to the end of the Daleks as, after rescuing Davros, with his warped mind not being truly Dalek he had realised how evil they were and needed to be stopped. Goaded on by Dalek Caan, and knowing the Daleks had sufficient force of numbers to take the universe by force, even without the Reality Bomb, the Meta-Crisis Doctor used the control panel to overload all of the Daleks' Dalekanium and blast it back destroying the Daleks and their ships and causing the Crucible to start to blow up.

The two Doctors and their companions escaped in the TARDIS, and although the Doctor offered, Davros refused to come with them and presumably died when the Crucible blew up along with Dalek Caan and all of the remaining Daleks. With the help of Mr Smith, K9, Ianto and Gwen; the Doctor was able to tow the Earth back to where it belonged with Sarah Jane, Mickey, Rose, Martha and Jack acting as co-pilots on the TARDIS. (DW: Journey's End)

Aftermath and legacy
The effects of the reality bomb broke down the Void, releasing the Cybermen who were previously locked away inside (DW: Doomsday), where they fell to Victorian era London at Christmas 1851. They were later stopped by the Tenth Doctor, who sent them into the Time Vortex, where they harmlessly disintergrated. (DW: The Next Doctor)

While the Doctor believed that all the Daleks to have been destroyed, one ship and three Daleks survived and escaped through time to 1941. While one of them waited in the badly damaged Saucer positioned behind The Moon, the other two came to Earth and used an Android who was programmed to believe he was a human who created the Daleks (refered to as Ironsides) for use as Britain's secret weapon in World War II so Winston Churchill could bring the Doctor to them. When the Doctor came one month later he was an incarnation not recognised by the Daleks but he soon revealed himself and the "Ironsides" revealed their true intentions and teleported back to their ship. The Doctor then followed them in the TARDIS, where the Daleks used the last Progenitor device which created 5 superior Daleks who then exterminated the three old ones. When their attempt to destroy London and then the Earth failed the new Daleks used a time corridor to escape and rebuild. (DW: Victory of the Daleks)

Shortly after the invasion, come September 2009, at least half of Earth accepted the existence of alien life, while the other half were in denial. The events, combined with other invasions, would lead to an increase in suicide due to crisis of faith. (TW: Children of Earth)

Future historical figure Adelaide Brooke, commander of the first mission to colonise Mars in the 2050s, was a little girl at the time of the attack on Earth. Both her parents were lost, and presumed killed. Her father's last words to her were to stay inside. She did so, however a Dalek later approached her house. It saw Adelaide, but realising she was a fixed point in time, did not exterminate her. According to the Doctor, Brooke's exploration of Mars (destined to end with her death) not only inspired generations of Brookes to reach beyond Earth, but also had a major impact on the human race leaving the confines of Earth. (DW: The Waters of Mars)

Despite the impact the invasion had on the people of Earth, the Doctor discovered that his companion, Amy Pond, despite being from 2010, knew nothing of it (DW: Victory of the Daleks). He later linked this to to the nature of the Time Field, a form of crack or entity that, one of which, can erase both people and events from history by unwriting their/its existence. This event was seemingly unwriten from time, much to the Eleventh Doctor's suprise, and explained for him why no one remembered the CyberKing walking over London (DW: The Next Doctor). When the cracks erase an event from history, it is known that the change to history is only minor, if nothing at all. In some cases, the consequences of the event still remain. (DW: Flesh and Stone). Although one might assume that the cracks' damage being undone would restore knowledge of these events to the public at large (DW: The Big Bang), humankind quickly reverts to not believing in aliens whatsoever. (SJA: The Vault of Secrets) The reason for this is explained by the fact that the only things that came back were those that were remembered by Amy, of which the Dalek invasion was not.