The Story Behind Coventry Carol
According to Wikipedia,
The "Coventry Carol" is an English Christmas carol dating from the 16th century. The carol was traditionally performed in Coventry in England as part of a mystery play called The Pageant of the Shearmen and Tailors. The play depicts the Christmas story from chapter two in the Gospel of Matthew: the carol itself refers to the Massacre of the Innocents, in which Herod ordered all male infants under the age of two in Bethlehem to be killed, and takes the form of a lullaby sung by mothers of the doomed children.
Within the pageant, the carol is sung by three women of Bethlehem, who enter on stage with their children immediately after Joseph is warned by an angel to take his family to Egypt.