# Code Girls by Liza Mundy - Blinkist

What’s in it for me? Get to know the unsung heroines of World War II.

As a woman in the 1930s, your career possibilities were essentially limited to one: schoolteacher.

Though some women sought out higher education, it rarely led to better job opportunities in a world where they were foremost expected to be a good daughter, wife, and mother.

So when the United States military began inviting educated women to serve the nation’s war efforts in  Washington, DC, thousands of American women seized the opportunity – often without knowing what awaited them.

These women served as code breakers throughout World War II, playing a crucial role in the success of the Allied forces.

Yet due to a combination of secrecy and sexism, no one knew about the contributions of these women.

These blinks aim to remedy that.

In these blinks you’ll learn  the tricks code breakers used to decipher enemy missives; which conspiracy theory led to the formation of the American army’s early cryptanalyst force; and how women writing and breaking codes led to the success of the D-Day landing.

Cryptography bureaus often took on female workers because of the work’s grueling nature.

Cryptography, or code making, is as old as human communication itself.

It dates back to some early point in time when a person first wanted to say something that not everyone was supposed to know.

Naturally, making codes is particularly useful in times of war.

During the Civil War, for example, the Confederates devised a cryptographic system so complex that it confused even them.

In the early 1920s, however, American code breaking lagged behind that of countries such as France and England.

In 1928, the US secretary of state even shut down military intelligence’s modest cipher bureau as it was bad manners to read other people’s mail.

But not everyone dismissed code breaking as immoral.

And those who did see its purpose tended to favor women for the job.

The assumption was that women were better able to focus intensely over long periods of time than men, who were seen as more intelligent but less patient.

The assumption overlooked the fact that good code breaking requires both patience and intelligence.

In order to understand how code breaking works, let’s take a look at the two types of covert message systems: codes and ciphers.

Codes are words, letters, or a string of numbers that represent words or phrases.

Sometimes codes are used for brevity, in the same way that OMG is used today.

But codes can also be used to disguise secret information from an enemy’s prying eyes; those meant to read the code could decipher it using a codebook.

Ciphers, on the other hand, are either a scrambling of letters known as transposition or a substitution of individual units with unique units – for example, substituting r for t.

During the Renaissance, ciphers such as the Vigenère square were created by lining up various alphabets into a table that could be referenced.

But with the development of radio and the telegraph, governments needed more security.

So they created cipher machines as well as developing complicated ciphers using mathematical equations.

Tackling messages intercepted by cable, airmail, or teletype – that is, cryptanalysis, or code breaking – involved many tactics.

In some cases, codes were cracked by stealing codebooks from the enemy.

But more often, cryptanalysts cracked codes by studying the frequency and placement of specific words, using mathematical equations, and deducing meaning through educated guesses.

In the summer of 1916, Indiana native Elizebeth Smith arrived at Riverbank Laboratories, in Illinois.

Riverbank was run by an eccentric millionaire called George Fabyan, who was hiring researchers to prove the theory that Sir Francis Bacon was the true author of William Shakespeare’s works.

Pioneering female code breakers helped pave the way for the pre-WWII US cryptanalytic force.

Bacon allegedly confessed his authorship in a cipher that was printed in Shakespeare’s First Folio.

Needless to say, it didn’t take Elizebeth long to question the existence of the code she was enlisted to crack.

Elizebeth’s fate changed when Fabyan shifted to position himself as an asset to the US government during World War I, transforming Riverbank into the government’s first code-breaking bureau.

Elizebeth and her new husband William Friedman, who had been hired for another Riverbank experiment involving genetics, suddenly found themselves at the helm of the nation’s primary code-breaking operation.

After the war, the army hired the Friedmans to work in Washington, notably paying Elizebeth half of her husband’s $3,000 salary.

And while William became the army’s leading code maker and cryptanalyst, Elizebeth gained widespread media attention for her work leading the cryptanalytic team which identified criminals during Prohibition.

Her acclaim set a precedent for female code breakers in the years to come.

But she wasn't the only female code-breaking luminary of the pre-war era.

A former math teacher from Illinois, Agnes Meyer Driscoll spent the 1920s and 1930s as the leading force in deciphering the ever-changing Japanese codes and ciphers in the navy’s small cryptanalytic office in Washington, DC.

One of Driscoll’s most impressive achievements was cracking a new Japanese fleet code in use since June 1939 that employed numbers rather than letters.

The Japanese fleet, as she found out, were using two separate codebooks.

The first gave a numerical code for each word or symbol to be encrypted.

The second book – called an additive book – gave a list of numbers to be added to those from the first book.

This would give a third set of numbers – the ones contained in the final message.

Driscoll figured this out in less than a year.

Her remarkable work enabled the Americans to enter World War II with at least some intelligence about Japanese internal communications.

But unfortunately, the Japanese changed their additive books in early 1941 – just before a now-infamous attack.

The army and navy competed to recruit female code breakers from elite colleges and small towns.

When Japan attacked Pearl Harbor on December 7, 1941, the United States was taken by complete surprise.

The preemptive military strike and Japan’s subsequent declaration of war made it clear that the US military urgently needed to strengthen its intelligence.

As it turns out, the navy had been scouting recruits for its cryptanalyst office even before the attack.

Agnes Meyer Driscoll may have been a great asset, but the office was still too small to handle the load of work that needed to be done.

And in addition to recruiting men from leading colleges and universities, the navy wanted patriotic women with a liberal arts education and a demonstrated talent for foreign languages, science, and math.

They also wanted the women to be attractive, so that they would marry and leave the navy sooner rather than later once the war was over.

It was in this context that, one afternoon in the fall of 1941, Wellesley College senior Ann White received a secret invitation to an interview; during it, she was asked if she liked crossword puzzles and if she had a fiance.

Ann responded yes and then no; she was then invited to take a course on code breaking.

If she passed, she would advance to Washington and work in a civilian position for the navy after graduation, for a salary of $1,800 per year.

Most importantly, she wasn’t to share information about her work or even mention the word “cryptanalysis” to anyone – including enlisted family members.

As the U.

S.

Army Signal Corps’ Signal Intelligence Service began to recruit its own code breakers, the two military branches competed to hire the best women.

The army focused its recruitment efforts on lesser-known southern colleges.

As the war progressed and the demand for code breakers grew, they also posted handsome officers in various public places, such as hotels in the South, to recruit small town school teachers.

In 1942, the United States made the controversial decision to admit women to its military.

The measure was embraced by thousands of women, who rushed to enlist in the navy as WAVES – Women Accepted for Volunteer Emergency Service – and the army as part of the Women’s Army Corps, or WAC.

Many of these women were also trained in code breaking; by the end of the war, there were an estimated 11,000 female code breakers across the US military.

This unprecedented force represented more than 80 percent of the navy’s domestic cryptanalyst personnel and 70 percent of the army’s.

The lives of the g-girls marked a societal shift for women.

The women who moved to Washington, DC to become code breakers were known by locals as government girls, or g-girls.

Of course, those outside of their workplace assumed that the g-girls were helping with menial office work.

In reality, their work was extremely intense, with seven-day shifts of up to twelve hours.

Yet for most of these women, life in the capital was also a time of unprecedented freedom.

Many women working at Arlington Hall, the army’s code breaking venue in Virginia, lived in the small rooms at Arlington Farms – a dormitory built to house 7,000 female workers.

Some girls boarded with locals around Washington and others – such as Virginia-born Dorothy “Dot” Baden and her close friend Ruth Weston – rented apartments on their own to escape the cramped dormitory living conditions.

To house their own cohort, the navy erected barracks for over 4,000 female coders at Mount Vernon Seminary in northwest Washington.

When they weren’t riding the streetcar or the bus to the beaches in Virginia or Maryland, the girls used their rare free time to travel to new, faraway places.

WAVES officers could go anywhere on a train for a discounted fare, and the code girls often travelled to New York or states even further away to visit their new friends’ families during their longer, 72-hour breaks.

Friendship wasn’t the only entertainment that kept these women occupied.

It might come as a surprise to some that the war was a time of frequent parties.

And while young men increasingly shipped off to fight, there was no lack of romance with soldiers and sailors who passed through the capital.

While many women had married or became engaged with haste before the war, others had come to Washington to escape those pressures.

Regardless of their marital status, all of the women wrote endless letters to men at war, often including portraits of themselves with notes scribbled on the back.

This was a crucial task for keeping up the war morale, and for her part, Dot Braden wrote to five soldiers simultaneously – though two were her brothers.

Although Dot was engaged to one of these soldiers, George Rush, she ended up marrying another suitor named Jim Bruce when the war ended.

They remained happily married until Jim passed away 62 years later.

A civilian army code breaker named Genevieve Grotjan played a key role in breaking Japan’s Purple machine.

You’ve probably heard of Alan Turing, the British mathematician who pioneered code-breaking methods at England’s Bletchley Park.

But there were also American women who contributed major cryptanalytic breakthroughs during World War II.

One of the biggest advances in code breaking during the war was cracking the Japanese cipher machine known to the Allies as Purple.

It was a job that Elizebeth Friedman’s husband William, working in the army’s Signal Intelligence Service, was determined for his team of civilian code breakers to accomplish.

Friedman passed on a variety of tricks and wisdom to his trainees.

One of these was the idea that if you looked at any code for a long enough time, it could be broken.

That’s because even the most complex ciphering machines used rotors and wheels, which meant that the cryptic patterns would ultimately repeat themselves.

Nothing in code breaking was ever entirely random.

Friedman’s team learned all of the nuances of romanized Japanese and studied machines on the market that the Japanese could have drawn upon for the Purple design.

They also used a technique called cribbing, in which certain words that had been broken or guessed acted as a starting point for deciphering the rest of a message.

In the case of Purple, Tokyo sometimes sent messages using both Purple and the old Red system that the US had already broken, giving the Americans clues about how the rest of the message could be read.

As pressure mounted, Friedman’s codebreakers hypothesized that Purple used a complex switching device in lieu of rotors when enciphering.

The only way to prove this was by comparing a Purple cipher to an already broken message – a crib – from a less complex Japanese system, in order to see if the pattern ever repeated.

In the early afternoon of September 20, 1940, Genevieve Grotjan shyly approached the head of the operation, Frank Rowlett, with her worksheets in hand.

Grotjan was an aspiring math professor who hadn’t been able to find a job – no university would hire a woman.

Now, less than a year into her tenure as a civilian army code breaker, Grotjan had figured out what her male colleagues had failed to catch: with her patience and sharp eye, she had found where the pattern repeated.

The break enabled the Americans to recreate the Purple machine without ever seeing the original build.

Grotjan’s discovery made it possible for the Allies to listen to Japanese communications on Purple for the entire duration of the war.

Working together, g-girls in Arlington Hall helped sink numerous Japanese ships.

Throughout the war, the g-girls faced sexism from male superiors, colleagues, and others outside of their workplaces.

But while hierarchical structures prevailed in the navy, work at Arlington Hall was comparably egalitarian.

At Arlington Hall, even newcomer code girls could become leaders of important units.

One such newcomer was twenty-three-year-old Bronxville native Ann Caracristi – known to her coworkers as Annie – who joined in 1942.

Annie had an English degree, but Arlington Hall supervisor Wilma Berryman – an early recruit hired by William Friedman – noticed that she also had a talent for engineering; she promoted Annie to be the leader of her research unit.

Annie and Wilma were determined to crack the Japanese Army’s code, which had yielded nothing to their many peers, male or female.

One idea they floated was that they might have a chance of breaking the code if they tackled the addresses appended to the messages.

Given that some messages had to be sent via Japanese naval radio circuits, they could use a crib from previously cracked naval messages.

After finding a crib in the Arlington Hall records, Wilma Berryman figured out that the additive for part of the address was 7250.

And though reconstructing the entire codebook – known as book-breaking – was a monumental task, Ann Caracristi turned out to have an exceptional talent for it.

In the early morning hours of April 7, 1943, Arlington Hall achieved another major breakthrough by cracking a Japanese water transport system code called 2468.

The intelligence 2468 produced spanned all Japanese shipping activities, including where ships were located and where they were going.

Solving the 2468 code also led to a domino effect of more breakthroughs, including the Japanese aviation code and a code that revealed the number of dead and wounded Japanese soldiers.

Before the end of the war, Arlington Hall was able to read every message that the Japanese Army sent.

In order to decode and sort the mail of the entire Japanese Army, Arlington Hall recruited a fresh batch of hires, who formed a mail-sorting assembly line.

The prolific decoding of messages through this system helped the Allies sink 43 Japanese ships and damage 22 in November 1943 alone.

As food and supplies were cut off from reaching Japanese soldiers, the effort ultimately contributed to the Allied victory in the Pacific.

Code girls broke and wrote codes that supported the D-Day landing in Normandy.

The code girls’ work on Japanese ciphers was pivotal in the US’s ultimate victory.

But their work reached beyond the Pacific.

In 1943, one group of WAVES members was sent to Dayton, Ohio to live on a campus called Sugar Camp.

There, the women helped build over 100 “bombe” machines – a design originally perfected by the British at Bletchley Park.

As they would later find out, these machines were made to decipher messages intercepted from the intricate German Enigma ciphering machine.

Intelligence gained from the Enigma and Purple machines influenced the Allied Forces’ planning of D-Day – in particular, their decision to land in Normandy.

Since the Purple machine was used by the Japanese foreign office, the Americans were able to read mail from Japanese diplomats in Europe that revealed that certain parts of the coastline along occupied France were less fortified than others.

Further intelligence came from German Army Enigma messages uncoded by the naval bombe machines and a message decoded in England detailing the defenses along the coast of Normandy.

In order to ensure that their attack was a surprise, the Allies created a program of deception, Operation Bodyguard, which would conceal the time and place of their invasion in occupied France.

The Allies needed to convince Germany that they would invade in multiple places with a central attack occurring in the Pas de Calais region.

Essential to ensuring that the Germans believed that this fake army was real – and would continue to believe so even after the invasion – were the g-girls.

Using the code-writing skills that many units had developed while monitoring the security of America’s own cryptographic systems, the women in the army and navy created coded messages about the location of the D-Day invasion using the American SIGABA machine.

The trick wasn’t for the Germans to read the messages themselves, but to deduce from the radio traffic that the invasion would take place in Calais with smaller landings in Norway and Denmark.

After months of meticulous planning, the Allies landed on the coast of Normandy on June 6, 1944, in the largest seaborne invasion in history.

Though invading the French coast required the sacrifice of many American lives, the deceptive plan meant that German fortifications were substantially delayed.

It was later estimated that the surprise landing saved 16,500 Allied lives.

G-girls were privy to both the horrors and the victories of the war.

When it came to sinking Japanese ships, the code girls took pride in their work.

Still, reading the details about the horrors of war was psychologically taxing.

News about American casualties, especially at the violent end of the war, troubled many.

In some cases, women were even aware that their enlisted husbands, boyfriends, or brothers were in danger without being able to do anything about it.

Fran Steen, a Naval recruit who had risen to become a lieutenant, was on duty when her team read a message saying that a Japanese kamaze raid would be targeting the navy destroyer her brother Egil captained.

Though the team notified the navy, nothing could be done to prevent the raid.

By a stroke of luck, however, Fran later discovered that her brother was one of the few survivors of the attack.

The fact that Japanese diplomatic messages passed through Arlington Hall also meant that the code girls were among the first Americans to learn when the war was over.

But this only came after a period of intense waiting.

The Japanese government’s refusal to surrender in 1945 resulted in an unprecedented wartime act when the United States detonated an atomic bomb over Hiroshima on August 6 and Nagasaki on August 9.

Though there were kamikaze attacks against American aircrafts and warships over the following week, on August 14, Arlington Hall translators received the message they had all been waiting for.

Translators such as Virginia Aderholdt, who had spent four years in Japan, had been following Japanese communications for months looking for clues.

They read intently as Japanese diplomats became increasingly discouraged by air raids on Japan and suggested ways to end the conflict in their conversations.

They also observed that the Japanese were planning to send their intent to surrender to neutral Switzerland.

On August 14, 1945, Virginia Aderholdt rushed to decipher the code that had been sent to the Swiss, which stated the Japanese intent to surrender.

Usually, translations were kept a secret.

But this time, the news spread across Arlington Hall like wildfire.

The girls would have to wait until President Truman announced the surrender that evening to share their joy with the outside world: after six long years, the war was finally over.

After the war, secrecy and sexism left the code girls with mixed career options.

A few months after the war was over, the women at Arlington Hall were thanked for their service and relieved of their positions.

Some time later, army operations officer Stephen Chamberlin publicly announced that code breakers were responsible for saving thousands of American lives and shortening the war.

But he didn’t mention that more than 10,000 of these cryptanalysts were women.

In fact, during her research the author found that much of the official information about the code girls’ contributions to the war effort had been classified for over 70 years.

She had to petition to have it declassified.

Given this, it came as no surprise that the women had mixed experiences when it came to their careers in the postwar years.

Back at Arlington Hall, some women remained and worked as code breakers for the first few years of the Cold War era.

A few of the women who didn’t eventually head home after that went on to work for the new National Security Agency, or NSA, which had merged army and navy code-breaking activities.

This included Arlington Hall’s own Ann Caracristi, who became the first woman to serve as the NSA’s deputy director.

Those who endeavored to have careers outside of government service met greater obstacles.

Due to the secretive nature of their work, women who had served in the navy were often denied the further education opportunities promised to veterans in the GI Bill.

One WAVES recruit, Elizabeth Bigelow, was rejected from three architecture schools; each said that it was reserving spots for veterans of the armed forces.

She couldn’t disclose the true nature of her contributions during the war effort, and ultimately resolved to marry and start a family instead.

The women held onto their secret up until the twenty-first century.

Remember Virginia Dot Braden, the civilian army code breaker from Virginia?

She had difficulty divulging certain words that related to her work to her family – even after, in her nineties, the NSA gave her the green light to share them.

She had never voiced code-breaking terminology outside of Arlington Hall.

By 2017, only a handful of the code girls were still alive to tell their stories.

Writing their history is therefore invaluable both as a way of honoring their collective and individual contributions and making known an inspiring chapter in the history of American women.

Covert code-breaking operations gave women access to careers that had previously been denied to them.

Final summary

Though their contributions were kept secret for years, we can now recognize these women for playing a crucial role in the Allied war effort and saving thousands of Allied lives.