The feast of Corpus Christi (Body of Christ) is celebrated to commemorate the institution of the Holy Eucharist.
One of ten holy days of obligation in the Latin church, the feast day falls on the Thursday after Trinity Sunday. However, in some countries, including the United States, the feast has been moved from Thursday to the following Sunday. This year Corpus Christi falls on June 15 but will be celebrated on June 18 in St. Mary Basilica.
For many years churches celebrated Corpus Christi with processions after Mass. The Blessed Sacrament , displayed in a monstrance, was carried through towns as people prayed and sang while venerating the Eucharist. Although the practice has waned in modern times, some parishes have short processions inside or outside their chuches while the Latin hymns “Pange Lingua Gloriosi” and “Tantum Ergo Sancramentum” are sung. Often the processions are followed by benediction and adoration of the Blessed Sacrament
The feast of Corpus Christi occupies a unique place in the history of St. Mary Basilica/Cathedral. At Mass on Sunday, September 18, 1862, Bishop William Henry Elder proposed a vow
that the congregation would observe the feast as a holy day of obligation in thanksgiving for the safety of the people of Natchez. The safety of Natchezians was threatened when the Union gunboat Essex shelled the city
for two hours on September 3, 1862. Pope Pius IX confirmed the vow on February 25, 1864. The congregation of St. Mary observed Corpus Christi as a holy day until 1913 when Bishop Edward Gunn, noting changing times, petitioned the Holy See for a release from the obligation. The vow, the approval, and the release are commemorated in the marble wall plaque near the altar of the Blessed Virgin Mary on the left side of the church.
The feast of Corpus Christi is a public holiday in many countries with large Catholic populations. The town of Corpus Christi in Texas was so named when a Spanish explorer discovered the area on the feast day in 1519.
Corpus Christi has been observed in the church since 1246 when it began in the diocese of Liege in Belgium.