The massacre of the innocents.

In the New Testament, the Massacre of the Innocents is the incident in the nativity narrative of the Gospel of Matthew (2:16–18) in which Herod the Great, king of Judea, orders the execution of all male children two years old and under in the vicinity of Bethlehem.

A majority of Herod biographers, and "probably a majority of biblical scholars," hold the event to be myth, legend, or folklore. 

The Catholic Church regards them as the first Christian martyrs, and their feast – Holy Innocents Day (or the Feast of the Holy Innocents) – is celebrated on 28 December.