Holy Innocents: their deaths are described in 2nd volume of the City of God. The babes were given reason so that they were martyrs for Christ.
City of God is private revelation, we do not base our faith on private revelation when it opposes dogma and tradition. Besides, even if they received reason, Herod didn't kill them because they were Christians, he did not even know that the infant Jesus was a Christian, he didn't know what a Christian was (2 - "the infliction of death by an enemy out of hatred for Christianity")
. He simply killed the infants to get rid of his competitor. Also, I would think that all of the dead infants since the beginning of the world till Christ's Ascencion, went to heaven in the same way as the Holy Innocents, they went to Paradise, Limbo of the Patriarch's, then after the Ascencion, Heaven was opened and they went to Heaven. Although, the Holy Innocents would have a higher position in Heaven, up with the Martyrs.