the episodes. The first, for "The Impossible Astronaut", was released on 25 March 2011. Prequels were subsequently released to promote "The Curse of the Black Spot", "A Good Man Goes to War", "Let's Kill Hitler", and "The Wedding of River Song". Broadcast The series was split into two halves, primarily for storytelling reasons, with the first seven episodes airing in early 2011 and the final six airing later in the year. The first half aired in the United Kingdom on BBC One from 23 April 2011, and the second half from 27 August. In the United States, the sixth series began airing on BBC America on 23 April; following "A Christmas Carol", this was the first full series to air on the same day in the US as the UK. However, "The Almost People" and "A Good Man Goes to War" were delayed by one week due to expected low numbers of TV viewers during the Memorial Day weekend. Space aired the premiere on 23 April for Canadian viewers, and "The Impossible Astronaut" was broadcast in Australia on ABC1 on 30 April. The series started screening in New Zealand on Prime on 19 May 2011. The second half of the series, beginning with "Let's Kill Hitler", was broadcast on 27 August 2011 on BBC America and on Space. ABC1 began the second run on 3 September. Some international broadcasts, including BBC America, contained a special introductory narration by Amy explaining the concept of the series before the opening credits. Moffat was asked to write the sequence; he called it a "bloody good idea" because it would make it accessible to new audiences, despite noting that diehard fans would not like it. Previous showrunner Russell T Davies was also a fan of the sequence. Home media All of the episodes from the first half of the series ("The Impossible Astronaut" to "A Good Man Goes to War") were released on 11 July 2011 on DVD and Blu-ray, entitled Doctor Who: Series Six, Part 1. This set included two featurettes called "Monster Files", which looked into the Silence and the Gangers. Doctor Who: Series Six, Part 2, covering episodes from "Let's Kill Hitler" to "The Wedding of River Song", was released on DVD and Blu-ray on 10 October 2011. It also contained two "Monster Files" on the Antibodies and the Cybermats. A 6-disc boxset containing all 13 episodes of the series and