The history of the feast is detailed in the third lesson of Matins:
"When Saint Louis, king of France, accepted from Baldwin II, emperor of Constantinople, the gift of the Lord’s crown of thorns, he sent to Constantinople two brethren, Stephen and James, of the Order of Preachers. In the year 1239, on the day following Saint Lawrence’s feast, they brought the crown to Sens, to the king. With great solemnity, it was borne to Paris and was finally placed in the royal palace, in a chapel built by Louis himself. The precious treasure, profanely stolen during the unhappy days of the French Revolution towards the end of the eighteenth century, was later restored and transferred to the metropolitan basilica. Louis however, made a gift of some thorns of the sacred crown to the Dominicans and commissioned them to celebrate, in the chapel dedicated to the crown, the anniversary of its reception there. The feast of the most holy crown of thorns was inserted into the calendar of the Order of Preachers about the middle of the thirteenth century."
Among some of the more beautiful prayers associated with this feast, is the Secret from the Mass:
The theme of kingship is a common thread that runs throughout this office, and is juxtaposed against the fact that it was the King of the Universe, the King of Kings, who wore this ignominious crown for the sake of our redemption. Long before the Feast of Christ the King was promulgated, the various prayers and antiphons of this feast anticipated the fact of Our Lords eternal kingship.
"Strengthen the might of Your soldiers, almighty king, that they whom the crown of Your Son encourages in the arena of this life, may at the close of the contest lay hold of the reward of life eternal: Through the same Lord…"
The collect prayer is:
"Almighty God, we who on earth recall the passion of our Lord Jesus Christ by honoring his crown of thorns, beseech you that we may be worthy to be crowned with glory and honor in heaven, by him; who lives and reigns with you…'