Historical evidence of Slaughter of the Innocents besides St. Matthew's Gospel? Besides Matthew 2:16,


  Herod perceiving that he was deluded by the wise men, was exceeding angry: and sending killed all the menchildren 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. 


What historical evidence is there of the Slaughter of the Innocents?
What historical evidence is there of the Slaughter of the Innocents?

Apart from the Gospel of St. Matthew, it seems that there is a serious lack of any recognized historical evidence for the slaughter of the Holy Innocents.


  “Then Herod, when he saw that he had been outwitted by the wise men, flew into a rage. He gave orders to massacre all the male children in and around Bethlehem who were two years old and under, in keeping with the time he had learned from the wise men.” (Matthew 2:16)


Many historians now seem to be of the opinion that this event mentioned in the Gospel of St. Matthew is of minor importance in the annuals of the deeds of Herod the Great. The Catholic Encyclopedia puts it as follows:


  The Greek Liturgy asserts that Herod killed 14,000 boys (ton hagion id chiliadon Nepion), the Syrians speak of 64,000, many medieval authors of 144,000, according to Apocalypse 14:3. Modern writers reduce the number considerably, since Bethlehem was a rather small town. Knabenbauer brings it down to fifteen or twenty (Evang. S. Matt., I, 104), Bisping to ten or twelve (Evang. S. Matt.), Kellner to about six (Christus and seine Apostel, Freiburg, 1908); cf. "Anzeiger kath. Geistlichk. Deutschl.", 15 Febr., 1909, p. 32. This cruel deed of Herod is not mentioned by the Jewish historian Flavius Josephus, although he relates quite a number of atrocities committed by the king during the last years of his reign. The number of these children was so small that this crime appeared insignificant amongst the other misdeeds of Herod. Macrobius (Saturn., IV, xiv, de Augusto et jocis ejus) relates that when Augustus heard that amongst the boys of two years and under Herod's own son also had been massacred, he said: "It is better to be Herod's hog [ous], than his son [houios]," alluding to the Jewish law of not eating, and consequently not killing, swine. The Middle Ages gave faith to this story; Abelard inserted it in his hymn for the feast of Holy Innocents:
  
  “Ad mandatum regis datum generale 
  nec ipsius infans tutus est a caede. 
  Ad Augustum hoc delatum risum movit, 
  et rex mitis de immiti digne lusit: 
  malum, inquit, est Herodis esse natum. 
  prodest magis talis regis esse porcum.
  (Dreves, "Petri Abaelardi Hymnarius Paracletensis", Paris, 1891, pp. 224, 274.)“


Historians do not always write down every event that has historically happened.


  Sometimes historians choose not to record an event, and their reasons cannot always be determined. In the nineteenth century Pope Leo XIII noted the double standard in critics for whom “a profane book or ancient document is accepted without hesitation, whilst the Scripture, if they only find in it a suspicion of error, is set down with the slightest possible discussion as quite untrustworthy” (Providentissimus Deus, 20).
  
  We should call out this double standard when critics demand that every event recorded in Scripture, including the massacre of the Holy Innocents, be corroborated in other non-biblical accounts before they can be considered to be historical. - Is the Massacre of the Holy Innocents Historical?