In the summer of 1919, an old four-story brownstone building on a corner of Fifth Avenue in New York carried a company sign: the “Universal Code Compiling Company.” It looked like an ordinary firm turning out commercial code books, but it was in fact the cover name for a secret cryptanalytic organization set up by the U.S. government. The people who worked there were not government officials but civilians paid in cash, and copies of telegrams exchanged between foreign embassies and consulates piled up on their desks. This organization, later known as “The Black Chamber,” was America’s first peacetime cryptanalytic bureau — meaning the first standing organization to survive rather than be disbanded once the war ended. After a decade of clandestine work, the organization was exposed to the world by a book written by its own hand, and its legacy stretches all the way to today’s U.S. National Security Agency (NSA).
Origins: MI-8, the Secret Organization Born of World War I
The Black Chamber’s roots trace back to 1917. Three weeks after the United States declared war on Germany, on April 28 of that year, the Army created MI-8 (Military Intelligence Section 8, the Code and Cipher Section) within its intelligence division to handle cryptographic work. The man who became its chief was Herbert O. Yardley. Born in Worthington, Indiana, the son of a railroad telegraph operator who taught him telegraphy, Yardley entered public service as a State Department telegraph and code clerk. In 1916 he decoded a 500-word coded telegram exchanged between President Woodrow Wilson and Colonel Edward M. House in just two hours, and used the feat to warn his superiors how weak America’s cryptographic systems were. This led to his commission as a reserve lieutenant in the Signal Corps in June 1917, and that July he was appointed head of MI-8.
MI-8 was strictly a wartime military organization. When the war ended and its funding and staff faced dissolution, Yardley persuaded Army leadership to keep the organization alive. Reorganized in May 1919 with joint funding from the State Department and the Army, it became the Black Chamber. The Army initially covered roughly 60% of the budget, though the financial burden gradually shifted toward the State Department; the annual budget was about $100,000 (roughly $1.9 million in today’s terms). In short, MI-8 (1917, a wartime organization) was reorganized after the war into the Black Chamber (1919, a peacetime organization) — and the label “America’s first peacetime cryptanalytic bureau” rests precisely on that qualifier “peacetime”: this was not an organization that existed only during the war and then vanished, but the first standing cryptographic organization to remain even after peace arrived.
Why New York?
In the summer of 1919, the organization relocated not to Washington, D.C., but to New York. Yardley’s own explanations were not consistent. Officially, he cited “legal constraints,” but he later also said he avoided Washington because it was “overrun with spies.” Beyond that, a practical reason often cited is that New York was home to the headquarters of major international telegraph companies such as Western Union. The more balanced reading is that both motives were at play — avoiding political scrutiny and gaining practical access to telegraph infrastructure.
The Black Chamber’s first office was a four-story brownstone at 3 East 38th Street, on the corner of Fifth Avenue, used from the summer of 1919 until July 1920. It then moved to 141 East 37th Street (July 1920–1924), and finally to 52 Vanderbilt Avenue near Grand Central Terminal (1924–October 1929), where it remained until it closed.
Silent Collaborators: The Secret Arrangement with the Telegraph Companies
The Black Chamber’s ability to obtain such a vast volume of foreign telegrams hinged decisively on the cooperation of commercial telegraph companies. The State Department and the War Department formed “special cooperative relationships” with Western Union, Postal Telegraph, and others, and in the early years these companies handed copies of telegrams exchanged by foreign embassies and consulates directly to Black Chamber analysts. Intelligence historian James Bamford has written that “virtually the entire American telegraph industry” eventually became caught up in this practice.
Over time, however, this cooperation visibly eroded. By the mid-to-late 1920s, Yardley himself admitted he had to rely on “somewhat clandestine methods,” which included illicit theft and bribery. One factor often cited behind the weakening cooperation is the Radio Act of 1927, which toughened criminal penalties for violating telegraph confidentiality, making telegraph companies far less willing to cooperate as readily as before.
The Washington Naval Conference: The Black Chamber’s Finest Hour
The Black Chamber’s most famous achievement came during the Washington Naval Conference, held from November 1921 to February 1922. At the negotiating table, Japan was publicly demanding a capital-ship tonnage ratio of 10:10:7 among the United States, Britain, and Japan. But Japanese diplomatic cables decrypted by the Black Chamber revealed that Tokyo was actually willing to concede to a ratio as low as 5:5:3 (or 10:10:6). Armed with the other side’s real bottom line, the American delegation used this intelligence to press Japan hard, ultimately securing a 5:5:3 ratio — 525,000 tons each for the United States and Britain, and 315,000 tons for Japan. This fact is confirmed authoritatively enough to appear not only in popular histories but in the Encyclopaedia Britannica, which states that “the State Department supplied information that the U.S. used to advantage at the Washington Naval Conference.” Yardley received the Distinguished Service Medal for this achievement.
This single episode alone proved the Black Chamber’s worth. Including its MI-8 years, over its twelve years of existence (1917–1929) until it closed, the organization is recorded to have decrypted more than 45,000 foreign diplomatic cables in total.
October 31, 1929: The Doors Close
The Black Chamber officially closed on October 31, 1929. The commonly told story goes as follows: newly appointed Secretary of State Henry L. Stimson, under the incoming Hoover administration, withdrew the State Department’s funding, and Stimson later explained the decision in his 1948 memoir, co-written with McGeorge Bundy, “On Active Service in Peace and War,” with the line, “Gentlemen do not read each other’s mail.”
Yet retelling this episode as a simple morality tale would not be accurate. To begin with, it is not even certain whether this quotation was actually spoken in 1929 or was a phrase crafted around 1947–48, when the memoir was being written — cryptologic historian Louis Kruh went so far as to publish a paper in the journal Cryptologia in 1988 directly re-examining the timing and authenticity of the quote. Moreover, the decision to close the organization was entangled with practical financial and organizational realities as well. The Black Chamber had originally been created by the Army, but to conceal its activities its budget had been routed through a State Department line item (roughly $40,000 a year), and the Army happened to be transferring the organization under the Signal Corps at the time as part of a unit reorganization. In other words, scholars point out that bureaucratic factors — budget and organizational politics — were intertwined with the State Department’s withdrawal of support. Interestingly, the NSA’s own historical account (“Herbert Hoover, the Black Chamber, and Food”) records that Yardley himself placed the blame for the closure not on Stimson but on President Hoover (though not all historians agree with this assessment). Hoover himself, in a letter written on July 12, 1954, to a military intelligence historian, responded on the matter that “I had nothing to do with it. It was the Secretary’s [Stimson’s] responsibility to run his own department.” There is also an interpretation that Stimson’s principle was not really a general one but rather an ethical objection specific to peacetime code-breaking aimed at friendly nations’ diplomats — ironically, the same Stimson, upon becoming Secretary of War in 1940, personally approved the budget and personnel needed for the “MAGIC” operation that decrypted Japanese codes during the Pacific War.
Memoir Controversy and Japan’s Response
Having lost his job overnight, Yardley found himself in financial straits and published his memoir, “The American Black Chamber,” in June 1931. Priced at $3.50, the book sold 17,931 copies in the United States alone, and cryptologic historian David Kahn called it “the most famous book on cryptology ever written.”
The claim that the book’s publication subsequently led Japan to strengthen its codes is widely repeated, but it should be treated as a matter of degree rather than an established fact. Accounts on this point use hedged language, saying the Japanese government became aware of America’s code-breaking capability, strengthened its own cryptographic capacity in response, and that this “may have” cost the United States dearly in the Pacific War that followed. What’s more, there is another fact worth adding: even before the book was published, Japan had already purchased the same information directly from Yardley himself, in June 1930. Facing financial hardship, Yardley sold the information to the Japanese embassy in Washington for $7,000 in exchange for a promise of secrecy — a transaction that came to light only in the 1960s, through James Bamford’s investigation. It is therefore possible that at least two channels — the direct 1930 transaction and the 1931 book — both contributed to Japan’s code strengthening, and the simplified narrative that “the book alone was the cause” is difficult to regard as accurate.
After the closure, Yardley was for a time treated as persona non grata by the U.S. government, but he later found employment as a cryptographic advisor to the governments of China (1938–1940) and Canada (1941), leading each country’s own “Black Chamber” (though his activities were constrained by American pressure). In February 1933, a manuscript in which he had compiled his achievements from the 1921–22 Washington Naval Conference (its title is recorded differently across sources, as either “Japanese Diplomatic Codes: 1921-1922” or “Japanese Diplomatic Secrets, 1921-22”) was seized by federal marshals under the Espionage Act. The manuscript was not declassified until 1979. This seizure prompted the push to enact the “Secrets Act” that same March, a law that later became codified as Title 18, Section 952 of the U.S. Code — the same statute applied in the 2013 Edward Snowden case.
Legacy: From SIS to the NSA
When the Black Chamber closed, its records and functions were transferred to the Army Signal Corps. The organization was reorganized into the Signal Intelligence Service (SIS), led by William Friedman, and from there traced a lineage through the Signal Security Agency (1943) and the Army Security Agency (1945) to today’s National Security Agency (NSA), established on November 4, 1952.
The NSA’s own historical materials officially designate the Black Chamber as “the first peacetime cryptanalytic organization in the United States.” At the same time, the NSA’s history series “History Today” also notes that conventional wisdom about Yardley has been reassessed over time — for instance, the once-common notion that he was somehow “anti-technology” has since been revised. This decade-long experiment, entangled with one man’s talent and ambition, national budgets, bureaucratic politics, and a nascent communications technology, ultimately left a legacy too complicated to be labeled simply a success or a failure. But one thing is clear: trace the roots of today’s largest signals-intelligence agency in the world back far enough, and you arrive at a handful of codebreakers working under a fake company sign in a worn brownstone building in New York.
References
- LegalClarity, “What Was the Black Chamber? America’s First Cipher Bureau” — legalclarity.org
- Wikipedia, “Black Chamber” — en.wikipedia.org
- Cromwell International, “Finding the American Black Chamber in New York” — cromwell-intl.com
- Wikipedia, “Herbert Yardley” — en.wikipedia.org
- Smithsonian Magazine, “The Spy Who Exposed the Secrets of the Black Chamber” — smithsonianmag.com
- Louis Kruh, “Stimson, the Black Chamber, and the ‘Gentlemen’s Mail’ Quote”, Cryptologia Vol. 12, No. 2 (1988) — tandfonline.com
- NSA Center for Cryptologic History, “History Today: Herbert Hoover, the Black Chamber, and Food” (2019) — nsa.gov
- Encyclopaedia Britannica, “Herbert Osborne Yardley” — britannica.com
- Wikipedia, “The American Black Chamber” — en.wikipedia.org
- NSA Center for Cryptologic History, “History Today: Herbert Yardley — Has the Story Changed?” (2018) — nsa.gov