The children mentioned in Matthew 2:16-18:

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.

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 othermisdeeds 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.)

But this "infant" mentioned by Macrobius, is Antipater, the adult son of Herod, who, by command of the dying king was decapitated for having conspired against the life of his father.

It is impossible to determine the day or the year of the death of the Holy Innocents, since the chronology of the birth of Christ and the subsequent Biblical events is most uncertain. All we know is that the infants were slaughtered within two years following the apparition of the star to the Wise Men (Belser, in the T©úbingen "Quartalschrift", 1890, p. 361). The Church venerates these children as martyrs (flores martyrum); they are the first buds of the Church killed by the frost of persecution; they died not only for Christ, but in his stead (St. Aug., "Sermo 10us de sanctis"). In connection with them the Apostle recalls the words of the Prophet Jeremias (xxxi, 15) speaking of the lamentation of Rachel. At Rama is the tomb of Rachel, representative of the ancestresses of Israel. There the remnants of the nation were gathered to be led into captivity. As Rachel, after the fall of Jerusalem, from her tomb wept for the sons of Ephraim, so she now weeps again for the men children of Bethlehem. The ruin of her people, led away to Babylon, is only a type of the ruin which menaces her children now, when the Messias is to be murdered and is compelled to flee from the midst of His own nation to escape from the sword of the apparitor. The lamentation of Rachel after the fall of Jerusalem receives its eminent completion at the sight of the downfall of her people, ushered in by the slaughter of her children and the banishment of the Messias.

The Latin Church instituted the feast of the Holy Innocents at a date now unknown, not before the end of the fourth and not later than the end of the fifth century. It is, with the feasts of St. Stephen and St. John, first found in the Leonine Sacramentary, dating from about 485. To the Philocalian Calendar of 354 it is unknown. The Latins keep it on 28 December, the Greeks on 29 December, the Syrians and Chaldeans on 27 December. These dates have nothing to do with the chronological order of the event; the feast is kept within the octave of Christmas because the Holy Innocents gave their life for the newborn Saviour. Stephen the first martyr (martyr by will, love, and blood), John, the Disciple of Love (martyr by will and love), and these first flowers of the Church (martyrs by blood alone) accompany the Holy Child Jesus entering this world on Christmas day. Only the Church of Rome applies the word Innocentes to these children; in other Latin countries they are called simply Infantes and the feast had the title "Allisio infantium" (Brev. Goth.), "Natale infantum", or "Necatio infantum". The Armenians keep it on Monday after the Second Sunday after Pentecost (Armenian Menology, 11 May), because they believe the Holy Innocents were killed fifteen weeks after the birth of Christ.

In the Roman Breviary the feast was only a semi-double (in other breviaries a minor double) up to the time of Pius V, who, in his new Breviary (1568), raised it to a double of the second class with an octave (G. Schober, "Expl. rit. brev. rom.", 1891, p. 38). He also introduced the two hymns "Salvete flores martyrum" and "Audit tyrannus anxius", which are fragments of the Epiphany hymn of Prudentius. Before Pius V the Church of Rome sang the Christmas hymns on the feast of the Holy Innocents. The proper preface of the Gelasian Sacramentary for this feast is still found in the Ambrosian Missal. We possess a lengthy hymn in honour of the Holy Innocents from the pen of the Venerable Bede, "Hymnum canentes martyrum" (Dreves, "Analecta hymnica") and a sequence composed by Notker, "Laus tibi Christe", but most Churches at Mass used the "Clesa pueri concrepant melodia" (Kehrein, "Sequenzen", 1873, p. 348). At Bethlehem the feast is a Holy Day of obligation. The liturgical colour of the Roman Church is purple, not red, because these children were martyred at a time when they could not attain the beatific vision. But of compassion, as it were, towards the weeping mothers of Bethlehem, the Church omits at Mass both the Gloria and Alleluia; this custom, however, was unknown in the Churches of France and Germany. On the octave day, and also when the feast falls on a Sunday, the Roman Liturgy, prescribes the red colour, the Gloria, and the Alleluia. In England the feast was called "Childermas".

The Roman Station of 28 December is at St. Paul's Outside the Walls, because that church is believed to possess the bodies of several of the Holy Innocents. A portion of these relics was transferred by Sixtus V to Santa Maria Maggiore (feast on 5 May; it is a semi-double). The church of St. Justina at Padua, the cathedrals of Lisbon and Milan, and other churches also preserve bodies which they claim to be those of some of the Holy Innocents. In many churches in England, Germany, and France on the feast of St. Nicholas (6 December) a boy-bishop was elected, who officiated on the feast of St. Nicholas and of the Holy Innocents. He wore a mitre and other pontifical insignia, sang the collect, preached, and gave the blessing. He sat in the bishop's chair whilst the choir-boys sang in the stalls of the canons. They directed the choir on these two days and had their solemn procession (Schmidt, "Thesaurus jur eccl.", III, 67 sqq.; Kirchenlex., IV, 1400; P.L., CXLVII, 135).