The debate on the date of the eruption of Vesuvius in 79 continues

Until today there is debate on which date the eruption of Vesuvius in 79 happened.

The eruption was longtime believed to have occurred on August 24th, based on the eyewitness account of Pliny the Younger, who observed the eruption from a distance. However, there is debate among historians and scholars regarding the question, if the day he gave for the eruption is exact.

Already very early scientists suggested that the eruption may rather have occurred in October or even November, based on evidence from archaeological excavations and the discovery of certain fruits and organic materials that would not have been in season in August.

Indeed, it must be noted that Pliny the Younger wrote his account of the eruption of Mount Vesuvius around 30 years after the event occurred in late 107 or early 108. He was not present at the eruption site, but instead witnessed the event from a distance while staying at his uncle’s house, Pliny the Elder, in Misenum. Pliny the Elder was the admiral of the Roman fleet at the time and sailed closer to Vesuvius to investigate the eruption, while the younger watched from far.

So, while Pliny the Younger’s written account of the eruption is considered one of the most important historical records of the event, he wrote it many years after the fact. When the eruption happened, he was 18. When he wrote his letter, he was 48. It may thus be asked, how accurate his memory was.

Also, there is doubt about the letter himself.

Pliny the Younger’s letter

Until today the letter from Pliny the Younger to Tacitus remains the best known and most commonly accepted historical source for the date of the Vesuvius eruption. Let us take a closer look at what it says:

According to its best known copy, the Codex Laurentianus Mediceus, it reads:

“Nonum kal. septembres hora fere septima mater mea indicat ei apparere nubem inusitata et magnitudine et specie.”

“On the ninth day before the kalends of September, around the seventh hour, my mother showed him a cloud unusual both in shape and size.”

(Gaius Plinius Caecilius Saecundus, Epistularum liber VI, 16, C. Plinius Tacitus Suo S.)

A majority opinion believes that Pliny the Younger states in his letter that the volcano erupted on nonum kal. septembres, i.e. nine days before the Kalends of September, a date that corresponds to 24 August. The ancient Romans counted inclusively, numbering both the start and end of a sequence. In this calculation, August 24 + 25+ 26 + 27 + 28 + 29 + 30 + 31 + September 1 = 9 days.

Pliny the Younger also describes how the day was hot and how Pliny the Elder, his uncle, took a bath and was barefooted, in the moment in which he learned of the eruption.

For centuries this information was considered reliable. Indeed, it was the only one which existed. The letter and a second one in which Pliny the Younger describes his own survival of the volcano eruption, are the only there are and even these only survive in four shamefully badly copied versions. Other sources mention the event, like Suetonius, but they don’t mention an exact date. Only Cassius Dione (Dio (1925). Roman History, Book LXVI, section 21Penelope.) comes close to giving one: He writes: “at the very end of the summer” (what can be interpreted as meaning August as well as September).

Archaeologists began soon to doubt the dating.

Let us see, who is right, Pliny or the archaeologists. And also if there could be an explanation fitting both.

Charcol inscription found in Pompeji.

The indices of the wine

In the excavation of the Vesuvian area, sealed by ash and mud, numerous agricultural remains were found. Scholars found also dried fruit, such as figs, dates, plums. Moreover, they discovered typically autumnal fruit, such as pomegranates in Oplontis, chestnuts, grapes, and walnuts.

There were also signs for the completion of the hemp harvest for sowing, a harvest that was usually carried out in September. Moreover there were indications for the completion of the grape harvest, carried out in September or October. Most, fresh grape-juice, had been sealed in amphorae, the dolea or dogli, round-shaped vessels in which the Romans stored liquids, such as oil and wine, and found at Villa Regina in Boscoreale.

These amphorae were only closed after a period of fermentation in the open air lasting about ten days and the eruption must have occurred after the grape harvest.

An explanation might have been an early harvest, as the Roman Empire coincided with a 500-year warm period, from AD 1 to AD 500. It caused the warmest period of the last 2,000 years called Roman Climatic Optimum.

Pliny wrote that the beech, which had previously only reached the height of Rome, pushed its habitat to the north of Italy. This hot period also favored the spread of viticulture by the Romans in most of Europe. That means, that also harvesting time could have been earlier than September close to Naples in the year 79.

In ancient Rome the Vinalia Rustica festivities took place on August 19th and served to propitiate the good weather during the ripening of the grapes. The official start to the harvest was then given by the festivity called Auspicatio Vindemiae. The period of the festivity varied every year, in relation to the ripening of the grapes.

In the monthly calendar of works, written by Columella, he mentions that grape harvest started in August in lands with remarkably hot climates, such as southern Spain and north Africa. At the beginning of September, harvest began in Italy in places near the sea and warm ones in general. One can thus conclude that the earliest date for harvest near Naples could have been the last week of August, but a date in September or even Ocober would have been much more likely.

A fresco showing fruit and a freshly baked bread.

The heating and the clothing

In addition to the above, typically autumnal objects have been found in houses and abandoned while in use, such as braziers in the House of Menander. A night could have been cold, but in the middle of a vulcano eruption? Many victims also wore heavy clothing. Maybe however, there is an explanation, as the braziers also served for cooking and the heavy clothing was doned to protect from the falling hot ashes. Pliny the Younger’s letter even speaks of people (including his famous uncle) strapping cushions on their heads to protect themselves.

The Text Variations

Analysing the various manuscripts of the Plinian text that have been preserved, it must be said that in truth there are as many versions as surviving copies. This is, what they say:

  • Nonum kal. septembres (nine days from the kalends of September, i.e., the 24th of August) (Codex Laurentianus Mediceus)
  • Kal. novembres (on the kalends of November, i.e., 1 November) (edition printed in 1474)
  • III kal. novembres (three days from the kalends of November, i.e., 30 October)
  • Non. kal. … (nine days from the kalends, gives no month) (15th-century version in Paris)

The presence of these variants point to transcription errors that the text has undergone by the copyists. Indeed, the original letter text of Pliny does not survive. The mostly used Papyrus was not durable and was prone to damage from moisture and insects. As a result, many ancient texts written on papyrus have not overcome to the present day in their original form.

Not even the oldest variant of Pliny the Younger’s text is immune to errors. The Roman writing in majuscules without signs and spaces and full of abbreviations did here certainly not help. It is also telling that all 4 copies are unsure of the same passages. A smudge or a damage to the papyrus will have given all of the copyists difficulties. Thus, the date of 24 August, derived from one of the variants of Pliny’s text, is far from certain and may not have been given by Pliny himself at all.

May be the eruption just happened a warm day in September. Or October. Or November…

The indice of the coin

A a numismatic find might indicate that the summer date is false altogether. Indeed, a silver denarius found on 7 June 1974 in the excavation at Pompeii, under the House of the Golden Bracelet (Insula Occidentalis) bears the inscription: “IMP TITVS CAES VESPASIAN AVG P M TR P VIIII IMP XV COS VII PP” –  “Emperor Titus Caesar Vespasian Augustus Pontifex Maximus, ninth time with the potestà tribunicia, emperor for the fifteenth, consul for the seventh time, father of the fatherland.”

The discovery of the Pompeian denarius with the indication of the 15th acclamation might allow us to state that the eruption occurred after the issue of this coin, thus in the year in which Emperor Titus held the 7th consulship (79), after the assumption for the 9th time of the potestà tribunicia, i.e., after 1 July and after the 15th acclamation as emperor, allowing us to move the terminus post quem beyond July.

Two inscriptions preserved in Seville and the British Museum in London dated 7 September and 8 September 79 may make it possible to put a date to the acclamation. In the two inscriptions, one a letter carved in a bronze epigraph by Titus to the decurions of the city of Munigua (today Villanueva del Rio), and the other a discharge diploma found in Fayyum, the 14th acclamation is given together with the dates of 7 September (for Titus’ letter) and 8 September (for the diploma), allowing us to state that the 15th imperial acclamation certainly took place after these two dates.

The terminus post quem of 7-8 September might ascertain that the eruption of Vesuvius took place after 8 September.

However, it is still possible, that the coin was struck earlier and the diploma and letter mentioning the 14th acclamation might have been dated long after the event, given that the objects had still to be transported to Spain and Fayyum. So the coin as such is not a 100 % sure evidence neither.


Other evidence supporting the thesis that the eruption occurred in autumn is to be found in an inscription located in 2018 in a house that was probably under renovation at the time of the eruption: the inscription, in charcoal, bears the date 17 October, but does not give the year as is usual for wall inscriptions relating to daily life in Pompeii. It most likely refers to the year 79, since charcoal inscriptions are easily erased.

Yet: The date of the charcoal inscription may not refer to AD 79 but may have been written earlier and been preserved because it was out of reach of people and weather. If left intact charcoal inscriptions can resist even for decades, as demonstrated by the charcoal inscriptions still legible on the vaults of the tombs of Porta Nocera. So the inscription is not yet a smoking gun, but a hint that should be placed in relation to the harvested wine, the coin and the fruits.

The text following the date is an ambiguous reading, but as its rather funny it shall be shared: “XVI (ante) K(alendas) Nov(embres) in[d]ulsit / pro masumis esurit[ioni]” – “On 17 October he indulged in immoderate eating”.

After all the above, it is much more likely that the eruption of Mount Vesuvius happened later than August. And may be Pliny the Younger wrote just that… But that is just a judgment based on indices… We keep looking for the waterproof evidence.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Create a website or blog at

Up ↑

%d bloggers like this: