The title comes from the lyrics Horace Lorenzo Trim composed for the bugle call known as 'Taps': "Day is done, gone the sun," etc. Oftentimes the tune is referred to as "Day is Done" or "Butterfield's Lullaby", the latter title named for Brigadier General Daniel Butterfield, a Union officer during the Civil War who is credited with composing the tune. Traditionally, 'Taps' is played at military funerals and memorials, hence the bugle call Pvt. Zane plays over the dead body of his sergeant.