Anschütz based his text on a 16th-century Silesian folk song by Melchior Franck (1579-1639), “Ach Tannenbaum”. Joachim August Zarnack (1777–1827) in 1819 wrote a tragic love song inspired by this folk song, taking the evergreen, “faithful” fir tree as contrasting with a faithless lover. The folk song first became associated with Christmas with Anschütz, who added two verses of his own to the first, traditional verse.
The custom of the Christmas tree developed in the course of the 19th century, and the song came to be seen as a Christmas carol. Anschütz's version still had treu (true, faithful) as the adjective describing the fir's leaves (needles), harking back to the contrast to the faithless maiden of the folk song. This was changed to grün (green) at some point in the 20th century, after the song had come to be associated with Christmas. After one final transition, the band and audience launch into “We Wish You a Merry Christmas”.
In 1935, Oxford University Press published an elaborate four-part choral arrangement by Arthur Warrell under the title “A Merry Christmas”, describing the piece as a “West Country Traditional Song”. Warrell's arrangement is notable for using “I” instead of “we” in the lyrics; the first line is “I wish you a Merry Christmas”. It was subsequently republished in the collection Carols for Choirs (1961), and remains widely performed. The earlier history of the carol is unclear. It is absent from earlier collections of west-country carols in 1822, 1823 and 1833, as well as from the great anthologies of 1861 and 1864. It is also missing from The Oxford Book of Carols (1928). In the comprehensive New Oxford Book of Carols (1992), the editors describe it as “English traditional” and “[t]he remnant of an envoie much used by wassailers and other luck visitors”. No source or date is given.
The greeting “Merry Christmas and a Happy New Year” is recorded from 1740. The English custom of performing inside or outside homes in return for food and drink is illustrated in the short story The Christmas Mummers (1858) by Charlotte Yonge, in which a group of boys run to a farmer's door and sing:
“I wish you a merry Christmas
And a happy New Year,
A pantryful of good roast-beef,
And barrels full of beer.”
After they are allowed in and perform a play, the boys are served beer by the farmer's maid.
The origin of this Christmas carol lies in the English tradition wherein wealthy people of the community gave Christmas treats to the carolers on Christmas Eve, such as “figgy pudding” that was very much like modern-day Christmas puddings. A variety of nineteenth-century sources state that, in the West Country of England, “figgy pudding” referred to a raisin or plum pudding, not necessarily one containing figs.