"I Heard the Bells on Christmas Day" is a Christmas carol based on the 1863 poem "Christmas Bells" by American poet Henry Wadsworth Longfellow. The song tells of the narrator's despair, upon hearing Christmas bells, that "hate is strong and mocks the song of peace on earth, good will to men". The carol concludes with the bells carrying renewed hope for peace among men.
During the American Civil War, Longfellow's oldest son Charles Appleton Longfellow joined the Union cause as a soldier without his father's blessing. Longfellow was informed by a letter dated March 14, 1863, after Charles had left. "I have tried hard to resist the temptation of going without your leave but I cannot any longer," he wrote. "I feel it to be my first duty to do what I can for my country and I would willingly lay down my life for it if it would be of any good". Charles soon got an appointment as a lieutenant but, in November, he was severely wounded in the Battle of New Hope Church (in Virginia) during the Mine Run Campaign. Coupled with the recent loss of his wife Frances, who died as a result of an accidental fire, Longfellow was inspired to write "Christmas Bells".
In 2000, the vocal group Rockapella began their album Christmas with an arrangement of the classic carol edition.
In 2002, choral composer Greg Gilpin set the words to the tune "Waly, Waly", an American Folk Song, in a sheet-music arrangement that is interesting because of its use of hand bells to illustrate the words. It omitted the last verse. 
In 2004, Pedro the Lion recorded a version for the Maybe this Christmas compilation.
In 2013, Echosmith recorded their version of the song and made it available to download for free on their website through the month of December.
In Chapter Five of his 1962 novel Something Wicked This Way Comes, Ray Bradbury described the carol as "immensely moving, overwhelming, no matter what day or what month it was sung." The whistled carol is an ironic presage of the evil that Cooger & Dark's carnival is about to bring to Green Town, Illinois.