The story begins back in 2013.
Eighty-nine fanatical Unioners crossed the line and went on to the pitch of the Stadion An der Alten Försterei, with mulled wine and biscuits to sing a bunch of Christmas carols.
And the number of attendees has grown from year to year - more than 10,000 attended the Weihnachtssingen event of December 2010. Since then, Christmas singing has become something which unites people of different generations and of different football clubs.
Father Müller recites the Christmas story. The choir of the Emmy-Noether-Gymnasium sets the tone and time. A small group of wind instrument players provides festive and cheerful music. The songbook and candle are free of charge - a small donation for the club's youth work is obviously greatly appreciated.