The Holy Innocents bore witness to Christ, not by speaking, but by dying: and so they won the martyrs' crown.
In the Divine Office for their feast (a fine composition), and in a part of it online, an apposite extract is given from St Quodvultdeus, Archbishop of Carthage and Metropolitan of Africa, confessor of the Faith under the Arian Visigoths.
The Coventry Carol, with its haunting tune, and sad words, to me sums up the horror of this commemoration – the soldiers hunting out the children, bashing them against walls, slaying them with swords, the unchilded mothers screaming...
From among many versions of the Carol seen sung on YouTube:
In sympathy with the sadness of this feast, until the last pre-Conciliar reforms, the Te Deum at Matins and Gloria in excelsis at Mass were not sung on Childermas day except it fall on Sunday; and, except on Sunday, not red, but purple was worn.
As often, the Dominican Breviary puts us in touch with medieval tradition, and provides not only proper antiphons, but also proper psalms for Matins of the Holy Innocents, the antiphons drawing on and interpreting those psalms in light of the feast:
Aña i. Novit Dominus vias Innocentium, qui non steterunt in viis peccatorum. (Cf. Ps 1:6a, 1b; & Ps 1)Aña ij. Rex terræ infremuit adversus Christum: quia rex in Sion constitutus super innocentium millia regnat. (Cf. Ps 2:1a, 2ac, 6ab; & Ps 2)Aña iij. Deus, judex justus, judica nos secundum innocentiam nostram. (Cf. Ps 7:12a, 9bc; & Ps 7)Aña iv. Ex ore infantium, Deus, et lactentium laude perfecta, destruis inimicum. (Cf. Ps 8:3; & Ps 8)Aña v. Judicabit Dominus pupillum, et viduam: et pluet super peccatores laqueos ignis. (Cf. Ps 10:7; & Ps 10)Aña vj. Mortis usuras rex impius exegit super innocentes: sed illi requiescunt in monte sancto Dei; malignus ad nihilum est deductus. (Cf. Ps 14:1b, 4a, 5ab; & Ps 14)Aña vij. Quis ascendit, aut quis stabit in loco sancto Dei? Innocens manibus, et mundo corde. (Cf. Ps 23:3-4a; & Ps 23)Aña viij. Innocentes adhæserunt mihi, quorum pedes avulsi sunt a laqueo mortis. (Cf. Ps 24:21a, 15b; & Ps 24)Aña ix. Filio regis datum est judicium: ut salvet innocentes filios pauperem: et humiliabit Herodem calumniatorem. (Cf. Ps 71:2b, 4bc; & Ps 71)
The last antiphon is instructive: Christ the newborn King, about Whose everlasting Reign the Royal Psalmist sings, is He to Whom judgement is given (by the Father); He shall save the innocent sons of the poor; and He shall humble Herod the proud.