Why the Date of Pompeii’s Destruction Is Still Debated

Despite the wealth of archaeological evidence unearthed from the ruins of Pompeii and Herculaneum, one fundamental question about the catastrophic eruption of Mt. Vesuvius in A.D. 79 remains unanswered: When exactly did it happen?

For centuries, historians accepted August 24 as the date of the disaster that buried the ancient Roman cities in ash and rock, killing thousands. Based in part on the recollections of a teenage eyewitness whose original letters have been lost, the traditional timeline has been challenged in recent decades. Some archaeologists point to discoveries suggesting Vesuvius might have erupted two months later, in late October.

Nearly 30 years after Vesuvius erupted, Pliny the Younger recounted the disaster in a pair of letters sent to the Roman historian Tacitus. About 17 at the time, the future Roman statesman watched from the safety of a villa 18 miles away on the Bay of Naples while the volcano spewed a towering plume of ash skyward. The calamity was seared into his memory for a deeply personal reason. His uncle and adoptive father, the renowned Roman naturalist and naval commander, Pliny the Elder, died while sailing toward the eruption to investigate and rescue victims.

Surviving copies of Pliny’s letters provide the only detailed eyewitness account of the disaster. The date recorded in his narrative has traditionally been interpreted as August 24 on the modern calendar. Discrepancies, however, crept in as scribes copied and recopied the original letters—now lost to history. Medieval manuscripts contain conflicting dates for the catastrophe, including October 24 and November 1.

Further doubts about the date of eruption arose shortly after large-scale excavations of Pompeii and Herculaneum began in the mid-1700s. Neapolitan bishop and scholar Carlo Maria Rosini challenged the August timeline based on botanical evidence preserved beneath the ash, including ripened figs, pomegranates, walnuts and chestnuts typically harvested in autumn.

In recent decades, a series of archaeological and scientific studies bolstered the case for an autumnal eruption. In 2018, the Archaeological Park of Pompeii announced the discovery of a dated charcoal inscription that corresponds to October 17; it was found on a wall in the newly excavated House of the Garden. Although it specified no year, archaeologists presumed the easily erasable charcoal could not have survived for long on an exposed wall and must have been written shortly before the disaster.

The charcoal, though, proved more durable than initially thought. In 2023, the park left another charcoal message on the same wall. Ten months later, it remained intact, raising the possibility that the original inscription dated to A.D. 78 or earlier.

Researchers have also pointed to the discovery of braziers typically used to heat rooms, autumn pollen and a silver coin possibly referencing an imperial honor bestowed upon Emperor Titus in A.D. September 79. Studies have found that the predominantly southward dispersal of volcanic ash is consistent with prevailing autumnal wind patterns. An analysis of plaster casts of victims showed that at least four wore woolen clothing, heavy garments that were seemingly ill-suited for the summertime heat.

DePauw University classical studies professor Pedar W. Foss argues that these findings have plausible alternative explanations and do not necessarily rule out an August eruption. Braziers were used for cooking as well as heating, he notes, and Roman firefighters wore woolen cloaks because their high thermal resistivity offered protection from intense heat.

Even the presence of autumn fruits is inconclusive, he says, since Romans preserved them for consumption outside their natural harvest seasons. “A house or a building that is destroyed at one moment in time doesn’t only have the items from that one period of time,” Foss cautions.

Other artifacts buried beneath the ash support Pliny the Younger’s August date, including mackerel preserved in the early stages of salting. The fish belong to a species that congregates in the Bay of Naples in late July and early August.

Complicating the archaeological findings, Pompeii was not entirely frozen in time by the eruption. Archaeologists have uncovered evidence that survivors returned to the devastated city, some to live in damaged buildings and others to scavenge valuables from the ruins. It wasn’t until the fifth century that the city was completely abandoned.

For his 2022 book, Pliny and the Eruption of Vesuvius, Foss conducted statistical and forensic analyses of all 79 surviving handwritten copies of Pliny’s account. In one transcription, he discovered that a 15th-century scribe had confused a “u” for an “n,” introducing the erroneous November 1 eruption date that proliferated with the advent of the printing press. By the 1900s, at least seven competing dates for the eruption had emerged.

While Foss’ research has strengthened the textual case for August 24, the scholarly debate continues. “Pliny the Younger may have been wrong,” the Archaeological Park of Pompeii stated in 2024. “In fact, archaeological excavations in the Vesuvian cities have provided elements to question the Augustan date.”

Foss, though, doubts Pliny would have misremembered the date of the cataclysmic event that nearly killed him, claimed the life of his uncle and left him heir to his uncle’s vast fortune and library. “His life completely changed on that day,” Foss says. “I think it’s exceptionally unlikely to believe he would somehow have gotten a day wrong.”

Pinpointing the specific date would do more than settle an ancient mystery. Foss says it would provide a fixed reference point for more precise seasonal studies of the ruins and modern climate research. It could also help scientists better calibrate their dating methods used at other archaeological sites.

Yet, a resolution remains elusive. In November 2025, archaeologists gathered in Pompeii for the first international conference devoted to determining the eruption’s date but failed to settle the long-running debate. According to Foss, “There wasn’t any consensus at the end of it.”