The Commemoration of the Passion of Christ was a feast listed in the pre-1962 Roman Missal as observed in some places, and kept on the Tuesday after Sexagesima. Its was instituted with the purpose of providing a devout remembrance and honour of Christ's sufferings for the redemption of mankind. It was the patronal feast of the Passionist Order.
Quoted from the Facebook Page of Restore the '54:
The Votive Feast of the Commemoration of the Passion of Our Lord Jesus Christ, which is a Duplex Maius, and is always the Tuesday after Sexagesima.
This feast can be found in the M.P.A.L. of the Roman Missal (and in this case, except for a proper Collect, the M.P.A.L. refers the priest to the Votive Mass of the Passion, "Humiliaverunt," in the Missae Votivae section of the Missal. Pope Leo XIII included these feasts of the Passion and Instruments of the Passion as Votive Offices in the Breviary before the revision of Divinu Afflatu from 1911-1913. However, the designation of it in the M.P.A.L. means unless it has always been celebrated in the Diocese where one resides or it is celebrated out of custom by an Order or country/territory as a whole, then it cannot be used. However, the exception to this rule is by retaining an indult of the local Ordinary or the Holy See.
For a history of this Feast I refer you to the 1911 Catholic EncyclopediaCollect:
Almighty and everlasting God, Who as a pattern of lowliness for mankind to follow, didst bring our Saviour to take flesh and undergo the cross: mercifully grant that as we celebrate the solemn commemoration of His Passion, so we may also deserve to have the schooling of His longsuffering and partnership of His resurrection. Through the same Lord Jesus Christ, Thy Son, our Lord, who liveth and reigneth with Thee in the unity of the Holy Ghost, God, for ever and ever. Amen.