A century-old cryptographic mystery has been solved using GPT-6 Astra. The AI successfully decoded a 1918 German radio message—encrypted with the complex ADFGVX cipher—that had remained unreadable for 108 years. By identifying the keyword for 'troop movement,' the AI revealed a report concerning the arrival of a British cruiser and Allied ships in Sevastopol. Historical verification confirmed the accuracy of the decryption, as the details align perfectly with the logs of the HMS Canterbury.