text: The Cable and Telegraph Section or Cipher Bureau was established on April 28, 1917, three weeks after the U.S. Congress declared war on the German Empire and began American involvement in World War I. It was headquartered in Washington, D.C., operated under the executive branch without direct Congressional authorization, and was relocated in the Army's organizational chart several times. On July 5, 1917, Herbert O. Yardley was assigned to head the Cipher Bureau; at the time, the unit consisted of Yardley and two civilian clerks. It absorbed the Navy's cryptanalysis functions in July 1918.
  After the end of World War I, the Cipher Bureau moved to New York City on May 20, 1919, where it continued intelligence activities as the Code Compilation Company, or the Black Chamber, under Yardley's command. Jointly funded by the Army and the State Department, the Cipher Bureau was tasked with breaking the communications of other nations, primarily diplomatic communications, as occurred during the Washington Naval Conference.
  According to intelligence historian James Bamford, the Black Chamber secured the cooperation of American telegraph companies such as Western Union in illegally turning over the cable traffic of foreign embassies and consulates. Eventually, "almost the entire American cable industry" was part of this effort. However, these companies eventually withdrew their support, possibly due to the Radio Act of 1927, which broadened criminal offenses related to breaching the confidentiality of telegraph messages.