This is a very ancient feast, celebrated by Orthodox, Roman Catholics, Anglicans, Armenians, and even a few Lutherans. It is also the titular feast of the Anglican Order of the Holy Cross, of which I am an associate. It dates from 326, when Helena, mother of the emperor Constantine, made a pilgrimage to Jerusalem. While there, she oversaw excavations for a basilica built on the site of Golgotha. Pieces of wood were uncovered which were accepted as parts of the cross upon which Jesus was crucified. A few centuries later, invading Persians carried off the sacred relics. They were recovered by the emperor Heraclius and returned to Jerusalem in 629, just in time for the conquest of that city by the new Islamic movement.

I include prayers of the feast from the Orthodox, Roman Catholic, and Anglican traditions.

Kontakion 4th Tone

Lifted up on the cross by your free will, Christ God, grant mercies to the new commonwealth that bears your name. Gladden our faithful rulers by your power, giving them victories over their adversaries. May your alliance be for them a weapon for peace, and invincible standard.

Roman Catholic

God our Father, in obedience to you, your only son accepted death on the cross for the salvation of mankind. We acknowledge the mystery of the cross on earth. May we receive the gift of redemption in heaven. We ask this through our Lord Jesus Christ, your Son, who lives and reigns with you and the Holy spirit, one God, for ever and ever. Amen.

Episcopal Book of Common Prayer

Almighty God, whose Son our Savior Jesus Christ was lifted high upon the cross that he might draw the whole world to himself: Mercifully grant that we, who glory in the mystery of our redemption, may have the grace to take up our cross and follow him; who lives and reigns with you and the Holy Spirit, one god, in glory everlasting. Amen.