Summer 1900 brought extreme peril to the International Legation Quarter in Peking as Boxer insurgents and Imperial Chinese troops laid siege to foreign diplomats. Trapped inside, the British Legation needed to transmit urgent intelligence to relief forces advancing from Tianjin. Communication relied heavily on telegraph cables and coded dispatches sent via brave couriers.
However, an unexpected disaster struck from within: the legation's primary telegraphic cipher book contained a critical printing defect. Months prior to the siege, a London publisher had misprinted several numerical lookup tables in the official diplomatic codebook issued to Asian consulates. When British officials attempted to encrypt tactical messages requesting immediate troop deployment and detailing Chinese artillery positions, the resulting code groups were completely garbled upon arrival at the command center.
Relief commanders received messages that decrypted into incomprehensible strings of nonsense, leading military planners to believe the legation had already fallen or that the telegraph lines had been hijacked by enemy agents. For nearly two critical weeks, the relief column delayed its advance while cryptographers desperately tried to reverse-engineer the corrupted substitution tables. The crisis was only solved when a lower-ranking consular officer remembered receiving a handwritten errata slip tucked into an old trade manifest months earlier.
Once corrected, accurate dispatches flowed again, allowing the Eight-Nation Alliance to coordinate the final, successful assault that lifted the siege.