Herod the Great was a ruthless King, scared of loosing his power and throne, so when he learned of the birth of the Christ, a King foretold from the line of King David had been born in the Bethlehem area he issued an order that all male infants in the area should be slaughtered, hoping to do away with this perceived threat to his throne and power.
The murdered infants never had an opportunity to know of Jesus, however they all died for the sake of Christ and today the Church remembers them - The Holy Innocents.