Question: In which military branch did the Heart to Heart singer serve?

full_context: Document 1: Dangerous (James Blunt song): "Dangerous" is a song by the British singer-songwriter James Blunt. It was released as the fifth single from his third studio album, "Some Kind of Trouble" on 26 July 2011. The song was written by James Blunt and Steve Robson.
Document 2: Love, Love, Love (James Blunt song): "Love, Love, Love" is the fourth single from James Blunt's second studio album, "All the Lost Souls". It is also his ninth single overall. It is the only song from the deluxe version of the album to be released as a single. It is also the first single released by Blunt to feature John Garrison, who replaced Malcolm Moore at the end of 2007, as one of the band members to perform on the track. The single was released on 7 November 2008, with a physical release appearing three days later. The song peaked at No. 121 on the UK Singles Chart, making it Blunt's lowest charting single to date.
Document 3: No Bravery: "No Bravery" is a pop rock song written by British singer James Blunt and Sacha Skarbek for Blunt's debut album "Back to Bedlam". The song was produced by Tom Rothrock and Jimmy Hogarth and received a positive reception from music critics. The song is written about Kosovo war while Blunt was serving there with NATO peacekeepers. It was released as the fifth single in April 2007, exclusively in France. The track peaked at No. 15 there. In the United States, "No Bravery" received heavy airplay but was not released as a single.
Document 4: So Far Gone (song): "So Far Gone" is the second single from English singer-songwriter James Blunt's third studio album, "Some Kind of Trouble". The single was released as a digital download single release exclusively in the United Kingdom on 3 January 2011. A live version of the song, recorded at Metropolis Studios, was included on the OpenDisc feature of "Some Kind of Trouble". Blunt performed the song live for the first time on "Comedy Rocks with Jason Manford" on 28 January 2011. Australian radio stations have picked up the song and are beginning to give it airplay as of March 2011.
Document 5: James Blunt: Return to Kosovo: James Blunt: Return to Kosovo is a 2007 documentary film recorded in September 2006, when musician and former British Army Captain James Blunt returned to Kosovo to perform a concert for serving NATO troops, and to visit places and people he had encountered whilst serving in Kosovo in 1999. The documentary was directed by Steven Cantor.
Document 6: The Heart of Dixie (song): "The Heart of Dixie" is a song written by Brett James, Troy Verges, and Caitlyn Smith, and recorded by American country music artist Danielle Bradbery. It was released on July 16, 2013 as her debut single after being crowned the winner of the fourth season of "The Voice", and the lead single of her eponymous debut album "Danielle Bradbery".
Document 7: Chasing Time: The Bedlam Sessions: Chasing Time: The Bedlam Sessions is a live album and DVD released by James Blunt in 2006 as a follow-up to his 2004 debut album, "Back to Bedlam". The set contains a live album from Ireland, as well as a DVD featuring a recorded performance at the BBC, music videos for "High", "You're Beautiful", "Wisemen" and "Goodbye My Lover", and interviews taken from various television appearances and studio sessions. The audio CD was also included as part of a deluxe package of "Back to Bedlam" that was available in the United States, thus meaning that this release was not issued there.
Document 8: Heartbreak on a Full Moon: Heartbreak on a Full Moon is the eighth studio album by American singer Chris Brown. The album is a double - disc, and was released on digital platforms on October 31, 2017 and has a physical release of November 3, 2017 by RCA Records.
Document 9: Billy Joel: On December 1, 2007, Joel premiered his new song "Christmas in Fallujah". The song was performed by Cass Dillon, a new Long Island based musician, as Joel felt it should be sung by someone in a soldier's age range (though he himself has played the song occasionally in concert.) The track was dedicated to servicemen based in Iraq. Joel wrote it in September 2007 after reading numerous letters sent to him from American soldiers in Iraq. "Christmas in Fallujah" is only the second pop/rock song released by Joel since 1993's River of Dreams. Proceeds from the song benefited the Homes For Our Troops foundation.
Document 10: Heartbreak on a Full Moon: Heartbreak on a Full Moon is the upcoming eighth studio album by American singer Chris Brown. The album is scheduled to release on October 31, 2017 by RCA Records. The track listing was announced by Brown on his Instagram account on May 1, 2017, and it will be a double album.
Document 11: Stay the Night (James Blunt song): "Stay the Night" is the lead single from English singer-songwriter James Blunt's third studio album, "Some Kind of Trouble". The single was released on 25 October 2010. The single received an exclusive advance-release in Austria on 10 September 2010. The song has been a success on the ARIA Charts, scoring his first top ten hit in Australia since 2005's "Goodbye My Lover".
Document 12: Some Kind of Trouble: Some Kind of Trouble is the third studio album by the British singer-songwriter James Blunt, released on 8 November 2010. On 6 December 2011, a deluxe version of the album was released, titled "Some Kind of Trouble: Revisited".
Document 13: Goodbye My Lover: "Goodbye My Lover" is a song by the English singer-songwriter James Blunt, written by Blunt and British songwriter Sacha Skarbek, for Blunt's debut album "Back to Bedlam" (2004). The song was produced by Tom Rothrock and Jimmy Hogarth and recorded in the home of actress Carrie Fisher. The single received a positive reception from music critics. It was released as the fourth single in November 2005 and reached the top ten in the United Kingdom, where it became Blunt's second top ten single. It also reached the top ten in Sweden, Australia and France. In the United States, "Goodbye My Lover" had modest success on the "Billboard" singles chart, where it reached number 66 on the "Billboard" Hot 100 due to digital downloads, even though the single was not yet released in the US. The song was formally released in the United States on 7 November 2006.
Document 14: Heart to Heart (James Blunt song): "Heart to Heart" is a song performed by British singer-songwriter James Blunt, from his fourth studio album "Moon Landing" (2013). It was released on February 3, 2014 as a digital download. The song has peaked to number 42 on the UK Singles Chart, the song has also charted in Australia, Austria, Belgium, Germany, Italy and Switzerland. The song was written by James Blunt, Daniel Omelio and Daniel Parker.
Document 15: Back to Bedlam: Back to Bedlam is the debut studio album by the English singer-songwriter James Blunt, released on 11 October 2004 through Atlantic Records. It is named after the famous psychiatric institution of Bethlem Royal Hospital, which is commonly known as Bedlam.
ground_truth: British Army
sub_queries: Heart to Heart >> performer Answer: James Blunt
James Blunt >> military branch Answer: British Army