Archive · 2 Oct 2026
GPT-6 Astra Decodes 108-Year-Old World War I Code
A German army message from World War I was written in a very difficult code.
GPT-6 Astra, helped by software developer Prinz, reportedly worked out what the message said.
The code used letters, numbers, and a secret keyword.
The message talked about an English ship going to Sevastopol.
It also said that an Allied group of ships would follow.
The decoded information matched records about HMS Canterbury.
The ship reached Sevastopol on November 24, 1918, and the squadron arrived two days later.
Historians still do not know why the message was sent before the cipher was officially supposed to be used.
GPT-6 Astra reportedly decoded a German World War I message that had remained unsolved for 108 years.
The ADFGVX cipher used the keyword "TRUPPENVERSCHIEBUNG," meaning troop redeployment.
The decoded message described an English cruiser and an Allied squadron traveling to Sevastopol.
The message matched naval records for HMS Canterbury, which arrived in Sevastopol on November 24, 1918.
A timing discrepancy remains: the message was sent on November 27, although the cipher key was scheduled for use on December 9.
- Who
- GPT-6 Astra and software developer Prinz decoded a message sent by German military officials.
- What
- They decoded an ADFGVX-ciphered message about an English cruiser and an Allied squadron.
- When
- The message was sent on November 27, 1918; the related ship arrived on November 24 and the squadron on November 26.
- Where
- The message concerned movements toward Sevastopol in the Crimean Peninsula, with HMS Canterbury traveling from Constantinople.
- Why
- German military officials used the message to report Allied naval movements.
- Cipher
- ADFGVX, a transposition and substitution system using a six-by-six grid.
- Keyword
- "TRUPPENVERSCHIEBUNG," meaning troop redeployment.
- Decoded subject
- An English cruiser arriving at Sevastopol, followed by an Allied squadron.
- Ship identified
- HMS Canterbury.
- Ship arrival
- HMS Canterbury arrived in Sevastopol on November 24, 1918.
- Squadron arrival
- An Allied squadron reached Sevastopol on November 26, 1918.
- Timing discrepancy
- The message was sent on November 27, 1918, although the cipher key was scheduled to enter use on December 9, 1918.