For decades, the iron helmets recovered from the seabed near Benicarló seemed to belong to the ancient world. They were found in the same underwater zone as Roman anchor stocks, amphorae and bronze helmets linked to much earlier Mediterranean activity. But a new scientific study has shifted the story forward by more than a thousand years.
The helmets, recovered in 1990 from the underwater site of Piedras de la Barbada off the coast of Castellón in eastern Spain, are now being identified as late medieval military equipment. Direct radiocarbon dating of textile linings preserved inside the iron shells places them mainly between the late 14th and early 15th centuries, a turbulent period when the Valencian coast was exposed to maritime raids, local militias and growing military pressure.
A rare survival inside corroded iron
The discovery is unusual not only because of the helmets themselves, but because of what survived inside them. Underwater iron artefacts rarely preserve organic material. Salt water, oxygen, microorganisms and corrosion usually erase textiles long before archaeologists can study them.
In this case, the sea created an accidental archive.
The helmets had fused into large concreted masses of iron, sediment and carbonate deposits. Within that hardened shell, fragments of plant-fibre textile survived in functional positions inside several helmet calottes. These were probably inner linings or padding, the kind of perishable material that almost never remains attached to medieval armour.
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Microscopic and spectroscopic analyses showed that the textiles were made of plant bast fibres, woven in a simple tabby structure with Z-twisted yarns. X-ray microtomography helped reveal the stratigraphy inside the helmets: marine sediment on the outside, textile below it, then iron corrosion products, and finally the original metal surface.
That layered microenvironment mattered. The corrosion products and carbonate concretions helped seal the textile away from the open marine environment, giving researchers a rare chance to date the helmets directly rather than relying only on shape or artistic comparisons.
Microphotographs of the collected samples: a) textile from the helmet interior (M1); b) fibre with Z-twist (M3); c) metallic corrosion products (M7); d) adhered marine sediment (M8) (figure by C. Álvarez-Romero). Credit: Frallicciardi M, et. al., 2026
A medieval cargo, not an ancient relic
At least 43 helmets have been identified in the Benicarló assemblage, though the true number may be higher because some remain trapped inside the concreted blocks. Their forms include hemispherical iron calottes, some with longitudinal crests, and one faceted, ogival helmet comparable to late medieval kettle-hat traditions.
Earlier assumptions linked the assemblage to the ancient material recovered from the same underwater site. The new study challenges that. Five textile samples were radiocarbon dated by accelerator mass spectrometry in two independent laboratories. Four results point to a coherent late medieval horizon, centred between the late 1300s and early 1400s. One sample produced a much later date, between the late 15th and early 17th centuries, but the researchers interpret it as an outlier, probably caused by contamination or intrusion of younger organic material.
The result is a sharper historical picture. These were not Roman helmets. They were likely practical, non-elite infantry helmets, probably made before European armour production became more standardized in the 15th century.
Three groups of the Benicarló assemblage: a & b) correspond to the two blocks recovered at Piedras de la Barbada, currently housed in the Museo de Bellas Artes de Castellón (groups A and B); c) the detached and conserved pieces exhibited in the Museo de la Ciudad de Benicarló (group C). The images were produced from photogrammetric data (figure by M. Frallicciardi). Credit: Frallicciardi M, et. al., 2026
Weapons for a dangerous coast
The timing is important. From the mid-14th century onward, the Valencian coast faced increasing insecurity. Raids and piracy became recurring threats in parts of the western Mediterranean, especially along exposed stretches of coastline. Coastal defence systems expanded, fortified settlements became more important, and local militias or garrisons needed practical equipment.
The Benicarló helmets may fit into that world. They were not luxury objects made for aristocratic display. Their simple construction, compact proportions and repeated forms suggest equipment intended for soldiers who needed protection without the expense or complexity of full plate armour.
Their exact origin remains uncertain. They may have been produced in regional Iberian workshops, or they may have reached the coast through wider Mediterranean trade. Either way, the assemblage points to the movement of military supplies by sea at a time when warfare, piracy and coastal defence were reshaping daily life along eastern Iberia.
Medieval helmet parallels shown in contemporary art: an illustration from the Holkham Bible, c. 1330–1340, and a helmeted figure from Hans Multscher’s Christ before Pilate (1437), once part of the Wurzach Altarpiece and now held in the Gemäldegalerie, Staatliche Museen zu Berlin. Credit: British Library Images / Wikimedia Commons, Web Gallery of Art, public domain.
A small textile clue rewrites the find
The most compelling part of the study is the reversal it creates. The helmets were first pulled into the orbit of antiquity because of the older material found nearby. But the fragile fabric inside them, protected by corrosion and seabed sediment, has now become the decisive evidence.
That makes the Benicarló assemblage one of the most important underwater finds for the study of medieval weaponry in the western Mediterranean. It also shows how military archaeology can change when researchers look beyond metal. Armour is usually dated by form, comparison and typology. Here, the true chronology came from something softer, hidden and easily overlooked.
The helmets were made for war, but their story survived because the sea sealed away their linings.
Frallicciardi M, Álvarez-Romero C, Doménech-Carbó MT, Graells i Fabregat R, Santoro AM. Radiocarbon dating and characterisation of textiles preserved in late medieval helmets from Benicarló (Castellón, Spain). Antiquity. Published online 2026:1-20. doi:10.15184/aqy.2026.10341
Cover Image Credit: Details of the overlapping helmets from different viewpoints. Frallicciardi M, et. al., 2026