Feast of the Holy Innocents and the Coventry Carol

The Coventry Carol was part of a 16th century mystery play depicting the slaughter of the young boys in Bethlehem as described in St. Matthew's Gospel, chapter 2, verses 16-18:

Then Herod perceiving that he was deluded by the wise men, was exceeding angry; and sending killed all the men children that were in Bethlehem, and in all the borders thereof, from two years old and under, according to the time which he had diligently inquired of the wise men. Then was fulfilled that which was spoken by Jeremias the prophet, saying: A voice in Rama was heard, lamentation and great mourning; Rachel bewailing her children, and would not be comforted, because they are not. (Douai-Rheims translation).

Lully, lullay, Thou little tiny Child,

By, by, lully, lullay.

O sisters too, how may we do,

For to preserve this day

This poor Youngling for

Whom we sing

By, by, lully, lullay?

Herod the king, in his raging,

Charged he hath this day

His men of might, in his own sight,

All young children to slay.

That woe is me, poor Child for Thee!
And ever morn and day

For Thy parting neither say nor sing,

By, by, lully, lullay.

Lully, lullay, Thou little tiny Child,

By, by, lully, lullay.

Because Henry VIII proscribed these mystery plays, and the last authentic manuscript was burned in the 19th century, the words we have now are based on transcriptions. Here is a performance from Westminster Cathedral.

There is another famous hymn for this Feast, very ancient, by Prudentius, Salvete flores Martyrum.
John Mason Neale collaborated on a translation:

1. All hail! ye infant Martyr-flowers,
Cut off in life’s first dawning hours:
As rosebuds, snapt in tempest strife,
When Herod sought your Saviour’s life.

2. You, tender flock of lambs, we sing,
First victims slain for Christ your King:
Beneath the Altar’s heav’nly ray
With Martyr-palms and crowns ye play.

3. For their redemption glory be,
O Jesu, Virgin-born, to thee,
With Father, and with Holy Ghost,
For ever from the Martyr-host. Amen.