In 1825, a mysterious double edged sword containing a cryptic code was found in the River Witham near Lincoln in England. The 13th century sword contains an enigmatic 18-letter message running down the center of the blade, and cryptographers and linguists have been unable to crack it. The British Library is now appealing to the public for help in solving this 800 year old mystery.

The sword, which is currently on display at the British Library as part of the Magna Carta exhibition, has a steel blade with a sharply honed edge that is believed to have been manufactured in Germany. The cross-shaped hilt is associated with Christianity and would have been used by a knight in his duty to defend the church.

“It's typical of the type of swords medieval knights and barons would have used at the time of King John and the Magna Carta,” curator Julian Harrison told MailOnline.

“The blade is unusual as it has two fullers, or grooves, running parallel down its length on each side,” reports The British Museum . “A Viking origin has been suggested for the sword on the basis of the fullers, the pommel and the letter forms of the inscription. However, it is apparent that the pommel, inscription and the blade shape are more characteristic of Medieval European swords than those of Viking origin.”

The Medieval sword containing a mysterious inscription. Credit: The British Museum

The sword’s inscription is made down the weapon’s central grove and is inlaid with fine gold wire. The 18-letter message reads: NDXOXCHWDRGHDXORVI.

The language the message is written in is still unknown, which has added to the difficulty in cracking the mysterious code.

The MailOnline reports that suggestions so far include that it may be “a battle-ready phrase in medieval Welsh, the first letters from a poem, or even complete gibberish fabricated by an illiterate craftsman”.

Some members of the public who have written in to the British Library, have identified letter combinations that had meaning in Latin during the era of the sword. For example, ‘ND’ may mean ‘nostrum dominus’ meaning ‘our Lord’, while the letter ‘X’ may be for Christ.

“It's been suggested in the past that it's a religious inscription and the sword may have been dropped in the river on purpose [for religious reasons] which was not uncommon,' Harrison told the MailOnline. However, Harrison thinks the most probable idea is that the inscription is in medieval Welsh, and could be roughly translated to “No covering shall be over me,” meaning that the owner of the sword must be ready for battle at all times.

The British Library is welcoming all suggestions from the public to help solve this centuries-old mystery.

The sword is on display as part of the library's exhibition Magna Carta: Law, Liberty, Legacy, and is displayed in connection with a 14th century manuscript of the Grandes chroniques de France. The old text is open at a page that depicts the French invasion of Normandy in 1203 with soldiers using swords that closely resemble the sword with the undeciphered inscription.

The page from the 14 th-century manuscript displayed alongside the Medieval sword in the British Library exhibition. Credit: The British Museum.

Featured image: The 18-letter message running down the central groove of a Medieval sword. Credit: The British Museum.

By April Holloway