This artwork by Tissot shows soldiers of Herod murdering boys under the age of two. Herod had been waiting to hear back from the three magi on the whereabouts of the Christ child (so he could kill him), but they never came back. Angry, Herod deployed his troops to massacre the young boys you see in the image. The boys are known as the Holy Innocents, and they are the first martyrs to die for Jesus Christ.
"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. — Matthew 2:16-18