By the time the United States joined WWI, German culture was already ingrained in American culture. Many Christmas traditions originated in Germany and become such an American tradition that it was impossible to suppress during the war. "O Tannenbaum" was written in the early 19th century and was a beloved German folksong before it was associated with the holiday. The song related the strength and endurance of a fir tree with that of the Christian faith and soon the tradition of placing a tree in one’s home for Christmas carried the song into the realm of caroling. While most know of the song and its origins, few Americans sang "O Christmas Tree" in its original German after WWI.

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"O Tannenbaum, o Tannenbaum,
Wie treu sind deine Blätter!
Du grünst nicht nur zur Sommerzeit,
Nein, auch im Winter, wenn es schneit.
O Tannenbaum, o Tannenbaum,
Wie treu sind deine Blätter!"