"Did castle defenders pour boiling oil on their assailants " Topic

…during a medieval siege?.

"It is a popular belief that during a medieval siege the beleaguered defenders would protect themselves by pouring boiling oil on their assailants. But is this actually true?

Boiling oil is a favourite with Hollywood (and nowadays with computer war games, too). History provides some accounts of its use. The Jewish defenders of Yodfat (Jotapata in modern-day Lower Galilee) are said to have used it against Vespasian's troops in AD 47. Other mentions include during the Hundred Years' War siege of Orléans (1428–29), the Great Siege of Malta (1565) and the siege of Sommières in the French Wars of Religion (1573)…."
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Amicalement
Armand

You can eat oil, sand and lead (from roofs) are not vital to your survival, even water could be in short supply inside a fortress. So boiling, burning or other oil would not be something you would use except in desperation.

For that matter firewood might be in short supply too. You'd need to keep the oil at a simmer constantly. An assault probably develops too fast to get a vat of oil up to temp from cold to be of any use.

Besides, it would probably be easier to dump the oil on the attackers, then throw some flaming torches down right after…