Feast of Saint Matthias - transferred

His feast day is February 24, but since that fell on a Sunday he is transferred to today.

From Lesser Feasts and Fasts:

In the nine days of waiting between Jesus' Ascension and the Day of Pentecost, the disciples remained together in prayer. During this time, Peter reminded them that the defection and death of Judas had left the fellowship of the Twelve with a vacancy. The Acts of the Apostles records Peter's proposal that "one of the men who have accompanied us during all the time that the Lord Jesus went in and out among us, beginning from the baptism of John until the day when he was taken up from us--one of these men must become with us a witness to his resurrection" (Acts 1:21-22). Two men were nominated, Joseph called Barsabbas who was surnamed Justus, and Matthias. After prayer, the disciples cast lots, and the lot fell to Matthias, who was then enrolled with the eleven.

Nothing further is told of Matthias after his selection. According to tradition he was an exemplary Apostle, but we know nothing more. Matthias seems an appropriate example to Christians of one whose faithful companionship with Jesus qualifies him to be a suitable witness to the resurrection, and whose service is unheralded and unsung.

Almighty God, who in the place of Judas chose your faithful servant Matthias to be numbered among the Twelve: Grant that your Church, being delivered from false apostles, may always be guided and governed by faithful and true pastors; through Jesus Christ our Lord, who lives and reigns with you, in the unity of the Holy Spirit, one God, now and for ever. Amen.
--the BB