The ancient napalm that burned on water and stayed a secret for 700 years

Science · Published 27 October 2026 Swipe more like this →

In short: Imagine a weapon so terrifying that it could set an entire fleet ablaze instantly, yet remained a state secret for seven centuries. Water, the obvious solution to fire, was useless against it. This was Greek Fire, the Byzantine Empire's ultimate technological advantage in naval warfare.

First appearing in 678 CE, Greek Fire was a highly flammable liquid used by the Byzantine Empire to defend Constantinople and dominate the seas. It is often described as the napalm of ancient warfare. The weapon was so strategically vital that Emperor Romanos II (r. 959-963 CE) explicitly declared that the secret formula must never fall into foreign hands, a mandate that was successfully upheld for over 700 years. The chemical composition was a closely guarded state secret, but modern scholars believe it contained a base of petroleum or naphtha, likely sourced from the Crimea region. Other suspected ingredients included quicklime, sulphur, resin, and potassium nitrate, with some theories suggesting the inclusion of gunpowder. The production process was extremely dangerous due to the liquid's volatility and required complex distillation technology that was advanced for the period. In naval combat, the Byzantines deployed the liquid from dromon-type ships—fast vessels capable of both sailing and rowing. Using bronze tubes equipped with syphon pumps and swivelling nozzles, they sprayed the liquid under pressure at enemy ships. The weapon was uniquely devastating because it burned exceptionally well on water and could not be extinguished by it. It incinerated rigging, sails, and hulls almost instantly, causing enemies to "shiver in terror." While the exact firing mechanism remains a mystery, a 2006 reconstruction by John Haldon using Crimean oil and reconstructed parts successfully fired intense flames 10 to 15 metres away. This confirmed the weapon's ability to incinerate anything in its path in seconds, maintaining its status as one of history's most effective military secrets.

theme hidden-mechanisms

mood awe

difficulty 3 topics [

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

Intellect Plus is a visual educational discovery platform for exploring fascinating facts and ideas. Brain Food, Not Brain Rot. What is Intellect Plus?

Related

• The ancient napalm that secured an empire's survival for seven centuries
• The lost secret of Greek fire: a medieval weapon system that burned on water
• The Byzantine Empire's secret weapon was a liquid flame that defied water
• The first recorded fire extinguisher put out flames by setting off gunpowder
• From ancient curses to modern plastic, the volatile history of naphtha explained
• Why choosing the greenest grocery bag is more complex than it seems
• The design philosophy behind a legendary first-person shooter
• Why our atmosphere acts as a planetary thermostat
• Who truly held the title of Byzantium's greatest ruler?
• Can machine learning turn existing surveillance cameras into weapon detectors?
• Who truly defined the peak of Byzantine power?
• Can the toxic side effects of ergot fungi be repurposed for medicine?

More in Science · Latest · A–Z · All topics