Songfacts®:

• This rock ballad opens with a clean-sounding electric guitar with no mics on the instrument, just on the amps. Guitarist Synyster Gates told MusicRadar: "We stumbled onto it by accident, actually. There were a few secrets in getting it, mainly that it's a baritone guitar with a capo on it so I could play it in open E standard tuning. It has a really sick, rich, sparkly sound."
• Gates told MusicRadar that the band were listening to "a lot of Elton John, some Ozzy ballads and some Zeppelin," for this song. He added: "The lyrics are inspired by my nephew, so the song has a very personal meaning to me."
• Speaking with Kerrang! magazine August 31, 2013, vocalist Matthew "M. Shadows" Sanders explained the background to the song's upbeat lyrics. "I had a little boy last summer," he said, "so this is a story that bridged the loss of Jimmy with new life. I tried to write it in a way that could be effective to people who have someone in their life that they love. For me, it's about my son."
  
  Owen James Sanders was born to Matthew and Valary Sanders on July 5, 2012.
• M. Shadows is not a fan of this song. "I think 'Crimson Day' is a throwaway," he said in a 2024 interview with Bradley Hall. "That's not a great ballad. We've had much better ballads. I think we've always done pretty good ballads, and 'Crimson Day' is the lowest on my list of things we've ever done."