On January 18, 1918 the German spy, Lothar Witzke was arrested carrying a codebook and an encrypted message.
The message was signed by the German minister in Mexico City and was studied by Herbert Yardley and Dr. John Manly of MI8 in Washington, DC. The message proved to be a transposition cipher. At the end of three days, Manly had transcribed the message, which was damning in that it identified the bearer as a secret agent!
While sources disagree on the exact date, when young Lothar Witzke crossed the international border into Nogales, Arizona on January 18, 1918 carrying a Russian passport, he was already well-known to the Military Intelligence Division, or MID. He had been under surveillance as a known German spy and was suspected as an accomplice in the sabotage attack on Black Tom Island in New York Harbor that occurred on July 30, 1916. That explosion was described as a thunderous blast, felt as far away as Philadelphia and Maryland. It rocked the harbor, shattered skyscraper windows, and pelted the Statue of Liberty with shrapnel.