After World War I, US cryptology was in disarray, with outdated codes and inadequate security. The urgent need for faster, more secure cipher machines sparked a global cryptographic arms race. On January 3, 1921, Elizebeth and William reported to the Army Signal Corps in Washington, DC’s Munitions Building, relieved to have escaped Fabyan’s control. William served as a reserve lieutenant earning $4,500 annually, while Elizebeth earned $2,200. Their boss, Joseph Mauborgne, was the cryptologist from their previous workplace, Riverbank.

US cryptology consisted of only three units with fewer than 50 employees total. The largest was Herbert Yardley’s “American black chamber” in New York (121), which read foreign diplomatic mail, especially Japanese messages. The Friedmans socialized with Herbert and his wife, Hazel, though William maintained a professional rivalry with Yardley.

While working in a windowless office, the Friedmans produced the Army’s first scientifically constructed paper codes. William then began analyzing cipher machines, searching for vulnerabilities. He defeated Edward Hebern’s rotor machine in 1923, achieving the first known solution of a wired rotor device, and he also conquered the Kryha machine. He briefly examined the German Enigma machine but saw no immediate need for serious analysis.

In spring 1922, Elizebeth resigned to write books at home. The couple moved to Bethesda, Maryland, and acquired a dog named “Krypto” and a cat called “Pinklepurr.” Elizebeth worked on a book about codebreaking for general readers and a children’s history of the alphabet. When officials couldn’t hire William, they approached Elizebeth. The Navy hired her in late 1922 to replace cryptologist Agnes Meyer Driscoll, but she left after five months when she became pregnant. Their daughter, Barbara, was born in 1923 after a difficult delivery, followed by their son, John Ramsay, in 1926. They hired a nanny named Cassie and moved back to DC, purchasing their first house at 3932 Military Road.

In 1925, Coast Guard Officer Charles Root asked Elizebeth to help break rum runners’ radio codes. The Coast Guard faced an overwhelming task: 203 patrol boats policed 5,000 miles of coastline against smugglers using sophisticated encryption. Elizebeth agreed to a 90-day contract on the condition that she could work from home. She solved two years of backlogged messages in three months and was hired full-time to break codes for all six US Treasury law-enforcement agencies—the “T-men.”

The smuggling syndicates, particularly the powerful Consolidated Exporters Corporation, used codes more complex than any military codes from WWI. Elizebeth built a comprehensive radio-intelligence system, coordinating with listening posts and training field agents. Her solutions exposed smuggling operations across both coasts and revealed connections to figures like gangster Tony “The Hat” Cornero and investor Joseph P. Kennedy, father of the future president. In a Texas case, she solved 650 messages, triggering a manhunt that ended with one fugitive murdered and another, Dan Hogan, developing a vendetta against her.

By 1930, Elizebeth analyzed roughly 25,000 messages annually with only one clerk-typist for support. She proposed creating a formal codebreaking unit and bound her solved messages into 30 volumes that formed a secret history of the smuggling trade. In July 1931, the Treasury approved her plan. Elizebeth became cryptanalyst-in-charge of a new US Coast Guard unit that served all six Treasury agencies, the first and only woman to run an American codebreaking unit. She hired and trained junior cryptanalysts and created a highly effective radio-intelligence organization.

Meanwhile, William’s work grew increasingly secret. In 1929, Secretary of State Henry Stimson shut down Yardley’s Black Chamber, believing peacetime codebreaking to be immoral. The following year, concerned about losing intelligence on Japan, the Army asked William to launch the Signal Intelligence Service (SIS). He hired mathematicians Abraham Sinkov, Frank Rowlett, and Solomon Kullback and showed them Yardley’s archived files. The SIS began the monumental task of solving Japanese diplomatic cipher machines codenamed “Red” and later “Purple.” Simultaneously, William designed the Converter M-134, which evolved with Rowlett’s innovations into the SIGABA machine. During World War II, the SIGABA would become the US’s primary high-level cipher device. It was never broken by any enemy.

The strain of the work affected William’s mental health. He grew withdrawn and suffered from insomnia, though Elizebeth supported him privately without labeling his condition publicly. Given the stigma and then-common treatment options, which included the “ice pick lobotomy” (151), this was a guarded choice. To resist the isolation imposed by their secret profession, the Friedmans used cryptology to connect with others. They exchanged cipher letters with their children, sent cryptographic holiday cards to friends, and hosted elaborate “cipher parties.” Keen to make extra money, William attempted (and failed) to sell a commercial board game called Kriptor. They also built an extensive personal library on cryptology, collecting rare books and unsolved puzzles. Fabyan unexpectedly sent them a rare 16th-century volume by Giambattista della Porta.

Elizabeth Wells Gallup died in 1934, still believing in her Bacon-Shakespeare theories. Fabyan died in 1936 after his health failed, having ordered many Riverbank cipher records burned to prevent embarrassment. William had hoped to use those documents for a comprehensive history of cryptology.

In 1931, Herbert Yardley published The American Black Chamber, revealing the secret operations of his defunct bureau. William was outraged, believing that the book threatened national security through its revelations about Japanese codebreaking. He heavily annotated his copy with refutations of Yardley’s many exaggerated claims. The scandal led Congress to pass the 1933 Secrets Act, preventing further disclosures. Yardley’s book, however, created public appetite for cryptology stories.

When Prohibition ended in 1934, smuggling syndicates shifted to narcotics. Elizebeth adapted and broke codes in multiple languages, including Mandarin. She exposed the Ezra brothers’ opium-smuggling operation and testified in major trials, including a key rum-running case in New Orleans, Louisiana, in 1933 and a narcotics trial in Vancouver, Canada, in 1938. The media became fascinated with her, publishing profiles that called her the “Key Woman of the T-Men” (167). A 1937 Reader’s Digest article reached over a million readers. By 1938, Elizebeth was the world’s most famous codebreaker, more celebrated than William, and this was a reversal he found amusing. She grew to dislike the publicity, which threatened her work’s secrecy.

In October 1938, William departed on a secret Pacific mission to deploy M-134 machines to military bases. He was at sea during Kristallnacht in November. Back in DC, Elizebeth fell mysteriously ill but concealed the severity of her condition from William. During his return journey, as nuclear fission was achieved and Nazi U-boats multiplied, William wrote a 30-page love letter to Elizebeth on tracing paper, acknowledging how much he owed to her support through his struggles. While standing on the ship’s deck and watching the calm ocean, he contemplated an uncertain future as the world edged toward war.