Research Explains Surprise That
H.L. Hunley’s Lantern Not Blue

By Christopher D. Rucker, MD
(August 2012 Civil War News)

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It turns out that the “surprises” of the recently conserved lantern from the Confederate H.L. Hunley submarine are not so surprising, after all (see Civil War News, July 2012).

For 30 years, authors have stated that a blue lantern was used by the Hunley to signal to shore after her successful attack. These statements were based on historical reports of “blue lights” as her prearranged signals, and a USS Housatonic lookout’s observation of a “blue light on the water.”

It turns out that in 1864, the term “blue light” had a very different meaning from what 20th century authors imagined.

“Blue light” was a pyrotechnic, handheld signal, a firework, used for generations by the world’s militaries for signaling, and in the civilian world for general illumination.

Modern researchers and authors failed to realize the 1864 meaning of “blue light” as known to 19th century witnesses and reporters, and have repeated the unfounded myth of the blue lantern until it has been ingrained in the public consciousness.

The Hunley’s lamp is what was called a “dark lantern” because it has a sliding internal shade which can instantly reveal or obscure the light. These were later called “police lanterns” since they allowed cops to stealthily approach and instantly illuminate suspected criminal activity.

It is no surprise that the lens of the Hunley’s dark lantern is not blue, since pyrotechnic blue light, and not a lantern, was the source of the Hunley’s signal.

Recipes for Civil War-era pyrotechnic blue light in the U.S. and C.S. Ordnance Manuals and other military texts produce an intense, white flame. Some earlier recipes had ingredients which imparted a dull, bluish tinge to the light.

By 1864, the military had dispensed with these ingredients and any pretense to a blue-colored signal, but retained the old moniker of “blue light.”

Modern researchers have been confused by the “blue” in “blue light” and were therefore surprised when the Hunley’s lantern was found to have a clear glass lens.

The rediscovery of the period meaning of “blue light” proves Hunley conservator Paul Mardikian’s statement that “blue light may refer to a signal technique common at the time rather than the color of the light.”

Reproduction pyrotechnic blue light, manufactured to military specifications, has been tested successfully in conditions comparable to those of  Feb. 17, 1864. Two YouTube videos demonstrate its manufacture and use: “Burning Blue Light” and “Making Civil War-Era Blue Light.”

This was the 19th century signaling technology familiar to sailors and civilians as “blue light.” There never was a blue lantern, and the final nail in the coffin of the blue lantern myth is the clear glass lens of the conserved dark lantern from the H.L. Hunley.


Christopher D. Rucker, MD of Boiling Springs, S.C., serves artillery with 18th and 19th century reenactment groups.