The Civil Wars were an indie folk duo comprised of singer-songwriters Joy Williams and guitarist/songwriter John Paul White. Some of the tracks on their debut album, Barton Hollow, deal directly with losses from their past. This song, for instance, concerns a family secret, mainly on Williams' side. She said: "We love to write about these things and hint at it while not giving the whole thing away. If the stories that we're singing about and the things that we're speaking of are true, hopefully they'll draw out the stories of the people who are listening, and that can create some invisible cycle of safety and exhilaration and freedom, and of being transported somewhere else for a little moment in time."
The Barton Hollow album was one of the most successful indie albums ever made, selling over 500,000 copies in America and winning the Grammy for Best Folk Album. They could have cashed in with a big contract for their next album, but the duo fractured as they were recording it in 2012. When it was finished in 2013, they were essentially broken up, so they couldn't tour to promote it. Columbia Records took it and gave it a powerful promotional push that helped it debut at #1, but with no sign of the (aptly named) Civil Wars, it quickly trailed off. They announced their official split in 2014.
The lyrics for "Mary, Did You Know?" were written by Christian singer and comedian Mark Lowry, after his pastor asked him to write a Christmas musical for their church. Southern gospel musician Buddy Greene later added music to his words.