There are actually two feasts of St Benedict celebrated each year in the Benedictine calendar: his heavenly birth is also celebrated on March 21 in the Extraordinary Form calendar; while the translation of his relics, July 11 is celebrated in the Ordinary Form calendar.
The subject of today's feast, the translation of the relics of St Benedict, is a subject of some dispute between the abbies of Monte Cassino and Fleury even unto this day as to who has the genuine ones!
Here is Fleury's version of the story from a medieval source, from GG Coulton, Life in the Middle ages:
"IN the name of Christ. There was in France, by God's gracious providence, a learned Priest who set about to journey towards Italy, that he might discover where were the bones of our father St Benedict, no longer worshipped by men. [Note: Monte Cassino, St Benedict's own monastery on a spur of the Apennines between Rome and Naples, had been destroyed by the Lombard barbarians in 580, and was not inhabited again until 718].
At length he came into a desert country some 70 or 80 miles from Rome, where St Benedict of old had built a cell whose indwellers had been bound together in perfect charity. Yet, even then, this Priest and his companions were disquieted by-the uncertainties of the place, since they could find neither vestiges of the monastery nor any burial-place, until at last a swineherd showed them, or hire, exactly where the monastery had stood; yet he was utterly unable to find the sepulcher' until he and his companions had hallowed themselves by a two or three days' fast. Then it was revealed to their cook in a dream, and the matter became plain unto them; for in the morning it was shown unto them by him who seemed lowest in degree, that St Paul's words might be true (I Cor. 1: 27), that God despises that which is held in great esteem among men; or again, as the Lord Himself foretold (Matt. 20:26), "Whosoever will be great among you, let him be your minister." Then, searching the spot with greater diligence, they found a marble slab which they had to cut through.
At last, having broken through the slab, they found the bones of St Benedict, and his sister's bones beneath, with another marble slab between; since (as we believe) the almighty and merciful God would that those should be united in their sepulcher who, in life, had been joined together in brotherly and sisterly love, and in Christian charity."
Having collected and washed these bones they laid them upon fine clean linen, each by itself, to be carried home to their own country. They gave no sign to the Romans lest, if these had learnt the truth, they would doubtless never have suffered such holy relics to be withdrawn from their country without conflict or war-relics which God made manifest, in order that men might see how great was their need of religion and holiness, by the following miracle. For, within a while, the linen that wrapped these bones was found red with the saint's blood, as though from open wounds on living whereby Jesus Christ intended to show that those whose bones are here so glorious would truly live with Him in the world to come. Then they were laid upon a horse which bore them over all that long journey as lightly as though he had felt no burden.
Again, when they journeyed through forest ways and on narrow roads, neither did the trees impede them nor did any ruggedness of the path obstruct their journey; so that the travelers saw clearly how this was through the merits of St Benedict and his sister St Scholastica, in order that their journey might be safe and prosperous even into the realm of France and the monastery of Fleury. In which monastery they are now buried in peace, until they I arise in glory at the Last Day; and here they confer benefits upon all who pray unto the Father through Jesus Christ, the Son of God, who lives and reigns in the unity die Holy Ghost, world without end. Amen.