On the early morning of 26 November 1866, before American Minister to France John Bigelow was out of bed, a secret encrypted cable from Secretary of State William Seward began arriving in the Paris telegraph office. The dispatch’s last installment was completed late the following afternoon. News and rumors about the lengthy encoded telegram spread rapidly through the French governmental departments and the diplomatic corps, but Bigelow maintained a determined silence. The first steamer from New York to arrive in France after the dispatch was written brought a reprint of the confidential cable in the pages of the New York Herald newspaper!
This strange episode in American foreign relations commenced a fascinating chapter in American cryptology history. Moreover, the event shaped American State Department code books for the next two generations and provoked a costly lawsuit against the US Government.