Could this pottery shard be a 1000-year-old hand grenade? Signs indicate yes

Archaeologists have analyzed the residue in four medieval ceramic shards and determined that one of them may have been used as a hand grenade, according to a recent paper published in the journal PLOS One. And the explosive used was likely made locally rather than gunpowder imported from China.

Byzantine soldiers used early versions of grenades in the 8th century CE, building on the “Greek fire” invented a century earlier. Instead of using Greek fire with flamethrowers, they placed the incendiary material in small stone or ceramic (and later glass) jars to make portable explosives. By the 10th century, the technology had spread to China, with Chinese soldiers packing gunpowder in fused ceramic or metal containers.

India probably also had grenade-like weapons. A 12th-century manuscript (based on an earlier Sanskrit work) describes a terracotta elephant filled with explosives with a fuse released on an invading army. A Chinese treatise of the mid-14th century refers to a “thunderclap cannon with flying clouds”, described as cast iron shells in the shape of a ball and about the size of a bowl, filled with gunpowder (“divine fire”). Similar grenades first appeared in Europe in 1467 and have been an important part of warfare ever since.

So it is perfectly plausible that grenades were also part of weaponry in 11th- and 12th-century Jerusalem. According to Carney Matheson, an archaeologist at Griffith University in Australia, and his co-authors of the latest PLOS One paper, small ceramic vessels (from a few inches to 20 centimeters in diameter) from the 9th to 15th centuries are commonly found in excavations across the Middle East. Many have conical bases and spheroidal bodies, and the ubiquity of these sphero-conical artifacts suggests that the vessels were used for many different functions.

Possible uses were: a plumb bob or loom weight, a liquid sprayer, a fire starter, a lamp, a smoking pipe or parts of a distillation apparatus. They would also probably have been used as containers for wine, honey, beer, medicines, fragrance oils, holy water, mercury or perfumes. And there is some evidence in historical documents that such ships were used as grenades. Residue analysis could help confirm those proposed uses, but according to Matheson et al., very few such experiments have been performed.

So the team decided to analyze the residue on four ceramic shards unearthed between 1961 and 1967 in the Armenian Gardens in Jerusalem, an area that was also the site of the Crusader’s royal palace. All the shards are housed in the Royal Ontario Museum. One shard (#741) was orange with a reddish-brown interior; shard #742 was gray green with a light green inner surface; shard #744 was greenish with a light gray interior; and shard #737 was dense and gray, both inside and out.

None of the shards have been treated by conservationists other than light brushing and rinsing with water. Since the artifacts were excavated in the 1960s, Matheson et al† was unable to take soil samples from the archaeological site. Still, they used existing available data on soil composition from that region of Jerusalem—mainly limestone and dolomite with lime spots decomposing into terra rosa and pale rendzina—for comparison with the residue analyses.

It was shard #737 that turned out to be of most interest to the researchers. The residue contained sulfur and mercury, as well as magnesium, nitrates, phosphorus, calcium (possibly derived from calcium oxide, a component of Greek fire), lead and iron. Matheson et al† noted that this suggests vegetable oils, glycerol and animal fats, consistent with the vessel used to contain oils, perfumes or medicines and as a fuel source for a weapon or a lamp.

It may have been used multiple times, but the authors believe the possibility of it being used as a grenade should be seriously considered. The thick walls could have withstood the rising pressure before detonation; the vessel was gray and undecorated; its size, shape and weight are about the optimal size for a hand grenade as described in historical records.

“These ships have been reported during the time of the Crusades as grenades thrown against the Crusader strongholds, producing loud noises and bright flashes of light,” Matheson said. Some researchers had suggested that the barrels were used as grenades and contained black powder, an explosive invented in ancient China and known to have been introduced to the Middle East and Europe in the 13th century. It has been suggested that black gunpowder has been introduced to the Middle East before, as early as the 9th-11th century in these vessels. However, this research has shown that it is not black powder and probably a locally invented explosive material.”

As for the other three shards, the residue from #741 contained a few fatty acids and only a small amount of sulfur that may have come from the surrounding soil. The authors concluded that this vessel was likely used as a container for oil. The residue from Shard #742 included animal fats, vegetable oils, resin, salts and mercury, with a little sodium in it. The sulfur, mercury and organics indicate that the vessel may have contained drugs.

Finally, the residue from shard #744 contained vegetable oils, animal fats, by-products possibly derived from fermentation (to make wine or beer), and sulfur. Matheson et al† concluded that despite its high sulfur content, it was also used to store medicines. “Sulphur has been used in alchemy, ancient medicines and ancient weapons, but it requires an oxidizing agent as a weapon, and an oxidizing agent was not identified in this residue,” the authors wrote.

DOI: PLoS ONE, 2022. 10.1371/journal.pone.0267350 (About DOIs).