The collect for today, The Feast of the Holy Innocents, from The Book of Common Prayer  (Canadian, 1962):
O ALMIGHTY God, who out of the mouths of babes and sucklings hast ordained strength, and madest infants to glorify thee by their deaths: Mortify and kill all vices in us, and so strengthen us by thy grace, that by the innocency of our lives, and constancy of our faith, even unto death, we may glorify thy holy Name; through Jesus Christ our Lord. Amen.
When wise men from the East visited King Herod in Jerusalem to ask where the king of the Jews had been born, Herod felt his throne was in jeopardy. So, he ordered all the boys of Bethlehem aged two and under to be killed. On this day, the church remembers those children.
The Massacre of the Innocents is recorded only in St Matthew’s Gospel, where it is said to be fulfillment of a prophecy of Jeremiah.
The church has kept this feast day since the fifth century. The Western churches commemorate the innocents on 28 December; the Eastern Orthodox Church on 29 December. Medieval authors spoke of up to 144,000 murdered boys, in accordance with Revelation 14:3. More recent estimates, however, recognising that Bethlehem was a very small town, place the number between ten and thirty.
This episode has been challenged as a fabrication with no basis in actual historical events. James Kiefer has a point-by-point presentation of the objections  with replies in defence of biblical historicity.
This is an appropriate day to remember the victims of abortion.
Artwork: Duccio di Buoninsegna, The Massacre of the Innocents (from front predella of the Maesta ), 1308-11. Tempera on wood, Museo dell’Opera del Duomo, Siena.