Sycorax invasion of Earth

The Sycorax invasion of Earth was an attempted invasion of Earth on 25 December, 2006 by the Sycorax in order to turn half of the human population into slaves via forcing surrender through blood control. The invasion was stopped by the Tenth Doctor when he defeated the Sycorax leader in combat. After Prime Minister Harriet Jones ordered the destruction of the retreating Sycorax spaceship, the Doctor organized her downfall in retaliation. (TV: The Christmas Invasion)

Origins
During the Slitheen crisis, the MP for Flydale North, Harriet Jones, emerged as a leader in dealing with the situation. Following the defeat of the Slitheen, the Ninth Doctor encouraged Harriet to run for Prime Minister, aware that history stated that Harriet would become Prime Minister for three consecutive terms and create Britain's Golden Age. (TV: Aliens of London, World War Three) Following this, Harriet was eventually elected Prime Minister in a landslide majority and under her leadership, Britain did in fact begin going into what many were calling a Golden Age. A project undertaken by Harriet's administration was the Guinevere One space probe launched to explore the Martian surface. However, the probe was intercepted and captured in orbit of Mars by the Sycorax spaceship. (TV: The Christmas Invasion)

Due to absorbing the energy of the Time Vortex in order to save the life of his companion Rose Tyler during the Battle of the Game Station, the Ninth Doctor regenerated into the Tenth Doctor. (TV: The Parting of the Ways) As Rose was shocked by this new incarnation of the Doctor, he agreed to return her home at Christmastime. (TV: Children in Need) However, the Doctor's regeneration was not complete and he collapsed until his body had finished changing fully. As such, he was bed ridden, cared for by Rose in her mother's flat. While the Doctor was unconscious, he released regeneration energy that traveled into space. (TV: The Christmas Invasion)