Historians' accounts give the day that Mount Vesuvius began erupting, spewing forth a devastating cloud of ash, stone and gas, as August 22nd, 79 AD.
But excavations in a previously unexplored part of Pompeii have uncovered an inscription that appears to be dated after the city, according to the accepted version, should have been destroyed.
Written in charcoal on the walls of a house, it reads: "XVI K NOV", which experts believe translates to 16 (in Roman numerals), calends (the Roman term for the first day of the month, represented by K), and November.
If we assume that means "the 16th day before the calends of November", that would date the inscription to October 17th.
Though the inscription doesn't give the year, archaeologists say it's unlikely the faint charcoal would have survived long without fading or being rubbed off.
What's more, it was found in a house that appears to have been in the process of being redecorated at the time Pompeii was destroyed, which suggests that it would have been plastered over shortly – had the occupants only had the time.
All these clues lead the site's archaeologists to believe that the inscription dates from just days before the eruption froze Pompeii in time, which they suggest could have been on October 24th, 79 AD.
The evidence for an earlier eruption comes from the one and only eyewitness account, written by historian Pliny the Younger who, aged 17, observed the disaster from the other side of the Bay of Naples.
His letters describing the eruption, while exceptionally detailed, were written some 25 years after the event. Plus, since the original documents were lost, the only records we have of them are copies made hundreds of years later during the Middle Ages – the various versions of which give different dates ranging from August to November.
Photo: Mario Laporta/AFP
Later historians have argued that the eruption must have occurred after the summer, citing the thicker garments victims seem to have been wearing at the time of their death, the fact that autumn fruits were found among the food stores, and that jars of wine – made from grapes that don't usually ripen until late September – had already been set to ferment.
Some geological evidence also supports the theory of a later eruption date: based on the distribution of the different layers of ash, researchers believe that the wind was blowing from the east when Vesuvius erupted; yet easterlies don't typically blow in the Naples area during the summer.
Italian Culture Minister Alberto Bonisoli, who visited Pompeii on Monday, called the inscription "an extraordinary discovery".
"It may well be that a scribe made a mistake and wrote something inaccurate... but perhaps we're rewriting the history books," he said.