The legacy of “A Canticle for Leibowitz” can be seen in the current flood of end-of-the-world novels, TV shows, and movies.

The abbey at Monte Cassino is situated atop a rocky hill about eighty miles south of Rome and was founded in 529 by St. Benedict of Nursia. It was there that the Benedictine order established the principles of Western monasticism. From Monte Cassino, monks went out and set up monasteries across the Christian world. Generations of scribes labored in the abbey’s library to copy texts and preserve artifacts that dated to antiquity. According to “Monte Cassino,” a history by Matthew Parker, by the start of the Second World War the monastery’s collection had grown to forty thousand manuscripts, including the majority of the writings of Tacitus, Cicero, Horace, Virgil, and Ovid. While the monastery’s perch on top of fifteen hundred feet of rock provided security, its location, near the main road between Naples and Rome, made the structure an attractive strategic asset. The abbey has been sacked many times: by the Longobards in 581, the Saracens in 884, and by Napoleon nearly a millennium later. Each time, it was rebuilt grander than before. And with each reconstruction the abbey took on more of the characteristics of a citadel.

From November, 1943, to May, 1944, the hill on which the abbey stood was at the center of one of the largest and bloodiest battles of the Second World War. Monte Cassino was a crucial part of the Gustav Line, a string of fortified German defenses that bisected Italy. In anticipation of the Allied push toward Rome, Hitler ordered that the Gustav Line be upgraded to “fortress strength.” Seeing the opportunity for a propaganda victory, the Nazis helped the monks box up many of the abbey’s treasures and transfer them to safety before the fighting began. Most of the monks then fled. The Allied command, believing that the Germans were using the abbey as a garrison and ammunition dump, made the controversial decision to bomb Monte Cassino. On February 15, 1944, American B-17s, B-25s, and B-26s dropped more than four hundred tons of explosives on the monastery. (Film of the bombing can be seen on YouTube.) Hundreds of civilians who had taken refuge there were killed. A handful of monks and other survivors left the abbey the next day. The fighting continued for another three months before a group of Polish soldiers planted their nation’s flag among the ruins of the monastery, signaling an Allied victory.

One of the American airmen who participated in the bombing of Monte Cassino was a young radio operator and tail gunner from Florida named Walter M. Miller, Jr. Miller, who enlisted in the Army after the attack on Pearl Harbor, flew on more than fifty combat missions in B-25 Mitchells above the Mediterranean region and the Balkans. Following the war, he got married, studied engineering at the University of Texas, and converted to Catholicism. In the fifties, he began publishing stories and novellas in Amazing Stories, Galaxy, Astounding Science Fiction, and other magazines_._ Miller also wrote scripts for the popular television show “Captain Video and His Video Rangers.” The list of writers for “Captain Video” includes some of the biggest names in midcentury science fiction: Arthur C. Clarke, James Blish, Isaac Asimov, and Jack Vance.

Miller is best known for the only novel he published in his lifetime, “A Canticle for Leibowitz.” Composed of a trilogy of novellas that originally appeared in The Magazine of Fantasy and Science Fiction,_ _”Canticle,” which was released in 1959, has never been out of print, selling more than two million copies. While it hasn’t attracted the following enjoyed by “The Lord of the Rings” or even “Dune,” it remains a hugely influential book and a landmark of post-apocalyptic fiction. Along with Ray Bradbury’s “The Martian Chronicles,” “A Canticle for Leibowitz” was one of the first novels to escape from the science-fiction ghetto and become a staple of high-school reading lists. Its legacy can be seen in the works of Gene Wolfe, Margaret Atwood, and many other speculative-fiction authors who came after him, as well as in the current flood of end-of-the-world novels, TV shows, and movies.

The book’s first novella, “Fiat Homo” (“Let there be Man”), is set at a monastery in the Utah desert some six hundred years after a nuclear holocaust known as the Flame Deluge. The war caused a backlash against learning and knowledge, called the Simplification, which wiped out almost all traces of civilization. Most of the people on earth are illiterate. Many are deformed by radiation. The monks who reside in the monastery are devoted to honoring the memory of Isaac Edward Leibowitz, a Jewish scientist at Los Alamos who was martyred for his efforts to safeguard scientific knowledge in the aftermath of the conflict. They collect and transcribe the “Leibowitz Memorabilia,” including shopping lists, technical documents, and circuit diagrams that they cannot even begin to understand. The protagonist of “Fiat Homo” is a bumbling but well-intentioned novice named Francis who, during a Lenten fast in the desert, accidentally discovers the fallout shelter Leibowitz used. This discovery results in Leibowitz’s elevation to sainthood. Francis makes the treacherous journey to New Rome to witness the canonization and is killed by mutant tribesmen on his way back to the abbey.

The second novella, “Fiat Lux” (“Let there be Light”), takes place hundreds of years later, in the thirty-second century. Like most middle parts of trilogies, it is the least compelling—”the long belly of a dachshund, slung ... between two pairs of sturdy legs,” as Peter Matthiessen characterized the second volume of his Watson trilogy. After more than a millennium, mankind is on the cusp of emerging from the dark ages brought about by the Flame Deluge. Hostility is brewing among the city-states (Denver, Texarkana, Monterey) that have risen out of the former American nation. A prominent scientist named Thon Taddeo, a latter-day Newton or Einstein, visits the monastery to investigate its holdings. He is astonished to find that one of the monks has created a working electric light, which is powered by a sort of treadmill. Taddeo believes the Leibowitz Memorabilia will lead him to breakthroughs in his work, but the abbot refuses to let Taddeo take items from the library back to Texarkana. Meanwhile, the abbey narrowly avoids being used as a military base for an attack on Denver.

The final part, “Fiat Voluntas Tua” (“Let Thy Will Be Done”), describes the beginning of another nuclear war, this time between the world’s two dominant powers, the Atlantic Confederacy and the Asian Coalition. It is the year 3781 and civilization has not only recovered but has developed beyond the level it was at in the mid-twentieth century. Nation-states once again have nuclear arsenals. Space travel between earth and distant colonies has become common. There is even a communication device in the abbey that is a combination of Google Translate and Google Voice. As the war begins, the abbot Dom Zerchi, instructs a group of monks to flee the earth for a colony near Alpha Centauri. They take the Leibowitz Memorabilia with them. After they depart, the abbey, which has stood for nearly two thousand years, is demolished by an atomic bomb. The abbot is crushed in the ruins. The final passages of the book are an eerie imagining of the Earth without mankind: