History of All Saints and All Souls
The Christian Feasts of All Saints and All Souls
During the first three centuries of Christianity the Church frequently had to operate "underground" due to the persecutions of the Roman state against her. During these periods there were many martyrs who died for their faith in Jesus Christ. The most renowned of these were honored locally by the preservation of the relics (if available) and by the celebration of the anniversary of their death, as a feast in honor of their birth into eternal life. As time passed, neighboring dioceses would honor each others martyrs and even exchange relics for veneration, the way the first century Christians kept the clothes and handkerchiefs touched by St. Paul (Acts 19:12).
At the end of the third century and the beginning of the fourth the most vicious of all persecutions occurred, that of the emperor Diocletian (284-305). The martyrs became so many that in some places it was impossible to commemorate even the most significant of them. The need for a common feast of all martyrs was becoming evident. This common feast became a reality in some places, but on various dates, as early as the middle of the fourth century. As far as Roman practice goes it is known that on 13 May 609 or 610, Pope Boniface IV consecrated the ancient Roman Pantheon as a temple of the Blessed Virgin and All Martyrs. Beginning with Gregory III (731-741) the celebration of a feast of All Saints was commemorated at St. Peters on November 1. Gregory IV (827-844) extended this feast to the entire Church.
The feast of All Souls developed more gradually, first with a monastic celebration of their departed on October 1st. This seems to have occurred first in Germany in the 900s. The patronage of St. Odilio of Cluny extended this feast to other monasteries, first of his own Order, then to Benedictines and others, from where it spread to dioceses, including Rome. It was only in 1915 that the special privilege of three Masses was granted to all priests by Pope Benedict XV.