The Eucharistic procession is also known as a Corpus Christi procession because of its association with the Solemnity of the Most Holy Body and Blood of Christ.
“The feast of the Blessed Sacrament was established in 1246 by Bishop Robert de Thorte of Liege at the suggestion of St. Juliana of Mont Carvillon. [It was] extended to the universal Church by Pope Urban in 1264. The office composed by St. Thomas Aquinas and customary procession was approved by Popes Martin V and Eugene IV. Celebrated in June, the first Sunday after the feast of the Trinity” (Modern Catholic Dictionary, by John A. Hardon, S.J.).
St. Juliana, a young Belgian nun in Retinne in the thirteenth century, while in prayer received the inspiration for a feast that celebrates and promotes the gift of the Real Presence of Christ in the Holy Eucharist, and from that moment, the Feast of Corpus Christi spread throughout the province, continent, and world.
The Feast of the Body and Blood of the Lord and the procession with the Blessed Sacrament, celebrating the sacrament and signifying God’s presence in our world and in our lives and reminding us of our common pilgrimage to Heaven, is a prayerful and edifying act of the entire Church.
Devotions are generally not mentioned in the Code of Canon Law. However, because of its importance in the life of the Church it is referred to in canon 944: “Whenever in the judgement of the diocesan bishop it can be done, a procession through the streets is to be held, especially on the Solemnity of Corpus Christ, as a public witness of veneration of the Blessed Eucharist.”