Were ancient lighthouses used as weapons?

The Burning Mirror on the top of the Alexandria Lighthouse which, in addition to guiding ships into harbour, had two other functions: the first being an early-warning system enabling watchers to see ships long before arrival at the Egyptian coast; the second being in cases where ships turned out to be hostile – by directing the mirror at a certain angle to reflect and intensify the sun’s rays and focusing it on incoming enemy ships, the ships would be set alight at sea.


Egyptology: The Missing Millennium : Ancient Egypt in Medieval Arabic Writings” by Okasha El Daly


I was flipping through an antique german-language Encyclopedia (Myers Konversationslexikon, 1903 Edition). I came across a page about lighouses.

The German word for lighthouse is Leuchtturm (light-tower). But the labels aroused my curiosity:

“Festfeuer” – fixed fire or focused-fire.

“Drehfeuer” – rotating fire

“Elektrisches Blitzfeuer” – electric lightning fire

“Fettgas Gluehlichtfeuer” – oil-lit fire.

“Zwillingsapparat fuer elektrisches Blitzfeuer” – Twin-Machine for electrical lightning fire”.

I’m fluent in German, but these expressions for lighthouses were unfamiliar. Modern German speaks of “lichtsignal” (light signal), “beleuchtung” (lighting), and “lampen” (lamps) when talking about lighthouses. The book makes it sound like the lighthouse could be used as a weapon. Even in the 1900s, light-ing was not commonly called lightning or even fire. The German word “Blitz” apart from its use to describe thunderstorm lightning, was used in World War I and II when referring to something active or used in attack.

To this day, german military calls their lighthouses warnfeuer (warning fire).

The idea of lighthouses as weapons seemed presumptious to me at first, so I left this article unpublished for two years. “Blitzfeuer” merely means “flashing light” and “festfeuer” just means “constant light”. “Drehfeuer” is simply rotating light.

Nothing mysterious about it. No need to read a mystery into everything, right? So the article sat dormant on this website for lack of evidence.

But a few days ago, I came across the quote you read at the beginning of this article. Subsequently I learned that at least half a dozen ancient arabic sources from medieval times references even more ancient times in which lighthouses were used as weapons.

This is a painting by Giulio Parigi (born 1571 in Florence), purporting to show the “death ray of archimedes”, a mirror that used the sun to burn the roman ships.

From the book Thesaurus opticus by the iraqi astronomer Ibn al-Haytham, born in 965:

I see three reflectors being used to start fires on ships.

The Lavoisier burning lens, image dated to 1770:

Similar burning lenses were demonstrated by inventors Joseph Priestly (born 1733) and Carl Scheele (born 1742).

Mainstream thought categorically denies that any such thing is possible:

I’m a little confused by the outright denial of the possibility. I’ve personally witnessed the convex magnifying glass burn paper, as in this video:

The ancients were using convex mirrors or convex glass, so why shouldn’t it be true? Why should the ancients have gone for thousands of years without noticing that the focused sunrays can burn things?

Maybe that’s why, on most old paintings, the Alexandria lighthouse it’s shown as smoking gun rather than being a beacon of light:

The most tiresome aspect of alt-history research is this the implied belief that our ancestors were incapable of anything interesting:

“God no!” this post says. They might as well be telling us that absolutely nothing interesting happened in the past.

The image below shows a Fresnel lens, pronounced Frenel lens.

Different types of Fresnel lenses have been in use in lighthouses since the early 1800s (according to the mainstream timeline).

A Fresnel lens can produce heat of more than 1000 degrees Celcius or 1800 Fahrenheit. That means it burns wood, plastic and even metals.


A 1845 blueprint for a dioptric apparatus:

Dioptric means that it’s convex glass capable of refracting light or turning it into a laser-like beam.

So we have here a device, stationed in most light houses, capable of producing a 1000 degrees hot beam. Maybe my idea of weaponized lighthouses isn’t as fantastical as I thought.

The Fresnel lens is claimed to have been invented in 1819, even though there are examples of it from 1789 (Thomas Rogers, Lighthouse in Portland), 1748 (Georges-Louis Leclerc), 1788 (Marquis de Condorcet) and 1811 (David Brewster). It’s interesting how hazy historians are over what did and didn’t exist in the 1700s.

Here’s a video where a random guy uses a small Fresnel lens to burn metal:

Can you imagine what a bigger fresnel lens is capable of?

The term “parabolic”, used in the ancient texts regarding the burning of ships, refers to a curve, similar to that of a diptric or convex mirror.

A post on a civil war discussion forum provides insight into how fresnel lenses were confiscated by the military during what is known as “the civil war” (bolding mine):

“…In 1851, a group of military officers produced a lengthy report (800+ pages) criticizing the generally poor condition of lighthouses, lighthouse keepers, and the USLHE. Congress responded by creating the Lighthouse Board in 1852. The Board was a combination of the Navy officers, Army engineers, the Secretary of the Treasury, and a few other civilians (usually at least one scientist or professor). The membership of the Board changed from year to year, but it brought much needed improvements and oversight. The Atlantic, Gulf, and Pacific Coasts (plus the Great Lakes and Mississippi River valley) were divided into Lighthouse Districts. Each district had an Inspector (a US Navy officer, usually a LtCmdr or Cmdr) and an Engineer (a Army officer, usually holding a rank between Lt. and Major). Engineers designed new lighthouses and oversaw construction and repairs; Inspectors checked stations quarterly to ensure Keepers were doing their jobs. Keepers were still appointed by the local Superintendent of Lights, a secondary title held by some Collectors of Customs.

Numerous Civil War were involved with lighthouses during the 1850s, either as Board Members, Engineers, Inspectors, or assigned special duty to a specific lighthouse project. …

…They also rapidly introduced the cutting-age Fresnel lens from France. A Fresnel lens is made of prisms that concentrate light rather than simply reflecting it and were a massive improvement all forms of earlier lighthouse optics. Eventually every US lighthouse had a Fresnel lens…

Along with the more obvious Federal property seized by the Confederate government like forts, they also assumed control of lighthouses…

Soon after Fort Sumter, the Confederate Lighthouse Board ordered all Southern lighthouses darkened. The reasoning was twofold: the lights were more helpful to the Union navy than the Confederates, and the Fresnel lenses were valuable items to be removed and secured for the duration of the war. Since most lighthouse keepers were local residents, most of them complied voluntarily with this order. Even if a keeper was reluctant to follow Confederate orders, the local populace and government officials could ensure compliance or take matters into their own hands. Fresnel lens were removed

The Confederates intentionally burned or blew up a number of lighthouses to deny them to the Union including Morris Island SC (outside Charleston Harbor), Tybee Island (mouth of the Savannah River, GA), St. Simons Island (near Brunswick, GA), and Sand Island (SW of Fort Morgan at the mouth of Mobile Bay). Other lighthouses are alleged to have been blown up or otherwise destroyed by either side of the war…

…In 1939, the lighthouse service merged with the US Coast Guard.

I had assumed lighthouses were civilian, not a military. Instead…

a) lighthouses were made and run by navy and army officers and engineers.

b) lighthouses were attacked and ordered shut down during the civil war.

c) Fresnel lenses were removed and locked away during the civil war.

If light houses can be used as weapons, all of this makes perfect sense. But if they were mere light beacons, one wonders why they need to be managed and maintained by navy and army.

Lighthouses have been among the first to be attacked in cases of war. Let’s take the lighthouse of Genoa as a random example, said to have been first built in 1128:

The tower also played a part, early in its career, in the ongoing feud between the Guelphs and Ghibellines; during one battle, the Ghibellines damaged it considerably

In 1318 and again in 1321, it was decided to dig a defensive trench around the tower, the better to protect it from damage in battle

In 1528, when Genoa was under French military occupation, the Genoese admiral Andrea Doria attacked the harbor with thirteen galeas, regaining control of the city. During these events, the Lanterna was badly damaged

The tower was shelled during the bombardment of Genoa by the French in 1684.

Management of the tower is under the authority of the Lighthouse Command Zone of the Marina Militare, and is directed from its center in La Spezia, which oversees all of the lighthouses in the region. The Marina Militare has been responsible for all lights on the Italian coast since 1910, and employs both military and civil technicians for the purpose.

I’ll let this serve as one example of hundreds, where the lighthouse was attacked in war.

A skeptic might argue that having light at night is important for military purposes.

But lighting is also important for attacking side and not a logical priority target.

Lighthouses before the 1700s, we are told, were not search-lights but mere towers that lit-up the surrounding area. The attacking military taking away the light source seems self-defeating to me…unless lighthouses doubled as weapons, in which case they should be the first target to be taken out.

The first lighthouse in the U.S. is claimed to have been “Boston Light”.

The first keeper of Boston Light was George Worthylake, who drowned, along with his wife and daughter, when returning to the island in 1718. During the American Revolution, the original lighthouse was held by British forces and was attacked and burnt on two occasions by American forces. As the British forces withdrew in 1776, they blew up the tower and completely destroyed it. The lighthouse was eventually reconstructed in 1783, to the same 75-foot (23 m) height as the original tower. In 1856 it was raised to its present height of 98 feet (30 m) and a new lantern room was added along with a 12-sided second order Fresnel lens.

Lighthouses have served as military targets throughout History.

Fresnel lenses, by the way, have been considered for large space telescopes becausee they can magnify views at large distances. And this article titled “Giant Fresnel Lens Deathray” warns how building one of these is “extremely dangerous” and will instantly set things on fire. And here’s a video where a Fresnel lens melts granite at 2300 Degrees Fahrenheit.

Shining a light on this topic reveals that lighthouses could even be used as weapons today.

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