Twelfth Hour is played in E3M3, E3M7, E6M3, and E6M7 in Wolfenstein 3D (DOS) as well as level 9 in Spear of Destiny (DOS). The song plays slow focusing on a strong bass line with deep, reoccurring bells.
Twelfth Hour is track 23 in the data files Wolfenstein 3D and track 11 in the data files of Spear of Destiny (DOS) (though it is not included in the demo release). Its title in the IMF meta data is "12TH" in Wolfenstein 3D and "TWELFTH" in Spear of Destiny. This song is not in the shareware release of Wolfenstein 3D.
Twelfth Hour was song of the month for April, 2013.