As the young abbey of Montecassino flourished in the 6th century they received numerous visitors and people seeking to become monks. They were not always friendly visitors that arrived, however. On one occasion the terribly cruel Goth leader named Zalla came, demanding gold and money and threatening physical harm. But St. Benedict's calm manner and loving demeanor was so remarkable to Zalla, that his life and the lives of others were spared. Despite succesffuly avoiding violence and destruction during these few unfriendly encounters in the early years of Montecassino, this was to change and St. Benedict foresaw it. He received a vision while praying which foretold the destruction of his monastery, and he knew there was no way to stop this terrible event from happening. But within this prophecy, St. Benedict took comfort in the assurance that not one monk would be harmed.

In the 30 years following St. Benedict's death, several others served as father and abbot of Montecassino: Costantino, Simplicio, Vitale, and Bonito. The final one, Bonito, was the one who witnessed St. Benedict's vision come true. The Longobards, violent conquerors from the north, arrived in 577 AD and in one night they destroyed Montecassino. The monks fled to Rome, bringing with them the original of The Rule of St. Benedict. Gregory the Great, a future Pope and author of the Dialogues (which included a biographical account of St. Benedict's life in Book II), encountered the Benedictine monks and St. Benedict's Rule probably for the first time when they arrived to Rome. Having brought the Rule of St. Benedict, their position in Rome further helped its diffusion through Italy. The Benedictine monks remained in Rome for the next 140 years, before eventually returning to the sacred summit to rebuild and reestablish Montecassino in the 8th century.