Book Review: CODE GIRLS by Liza Mundy (non-fiction history 2017 )

The Untold Story of the American Women Code Breakers of World War II

More than ten thousand American women served as code breakers during World War II. The army and navy competed for them, recruiting from top university graduating classes and from high school teachers. Told only that they would be doing important office work in the Nation's Capital, they were given a letter telling them where to report, and cautioning them to never talk to anyone about their work, not even family or fellow workers.

Armies have used codes for centuries. But when radio communication enabled real-time contact with ships at sea, airplanes, commanders on front battle lines, or diplomats in far countries, anyone with radio savvy could listen in. Secrecy demanded cryptic speech that an enemy would not understand. Anyone who could figure out the meaning could anticipate enemy action before it happened. With war approaching in 1939, Army and Navy geared up to detect enemy plans. Recruits were tested to detect high intelligence, especially ability in math and foreign languages.

The influx of hundreds of young women overwhelmed Arlington County, across the Potomac River from Washington. The government hastily built new apartment buildings and dormitories; officials went door to door asking residents if they had an extra room, or a basement apartment two or three girls might occupy. Ms. Mundy entitles one chapter “Twenty-Eight Acres of Girls.”

Many were from small rural towns; their ability to de-code developed as they worked. Washington was keeping track of nations all over the world, but the main focus was on Hitler's Nazi Germany, already at war with Britain and France, and Japan in its expansion through China and beyond. Both countries had complicated code systems which were changed every few days or weeks. Germany had developed a portable machine, “Enigma”, which automaticaly encoded German. It had three wheels, each with twenty-six positions. Varying their relative positions could create thousands of different ways of scrambling the letters of a message.

Japan had a similar device, the “purple machine” which would take phonetic Japanese (using the English alphabet to change Japanese writing and then scrambling the letters.) The British had already decoded Enigma's output, but the teams of both British and American decoders were stymied by the Japanese “Purple Code” for months. They had solved six of the letters, but could not crack the other twenty.

September 20, 1940, several team members were talking together, when a shy young recruit, Genevieve Grotjan, approached. “Excuse me,” she said, “I have something to show you.” She laid down a very long message in Japanese purple code, where she had encircled the position of the same two symbols appearing together four times in different spots. From her discovery, the team was able to deduce the rest of the code.

A number of factors conspired to affect the lack of preparedness at Pearl Harbor that brought America into the World War, but the code breakers had advanced far enough in the following year to achieve three major victories. Japan's progress toward Australia in 1942 was halted by the battle of the Coral Sea. Japanese aircraft carriers were astonished when, approaching Port Moresby, New Guinea, they met American planes from the carriers Yorktown and Lexington, who destroyed some of Japan's best pilots. No ships on either side saw the ships of the other, but the American decoders monitoring Japan's radio traffic directed the Navy to the spot where they could stop the Japanese.

A month later, the Navy was uncertain whether the Japanese designation “AF” stood for Alaska Force or for Midway Island, north of Hawaii. The coders sent a fake notice (in plain English) that Midway's water supply had broken down and soon detected Japanese messages that AF's water supply was short. Japan sent one force northward toward Alaska to draw off the American Navy but the Americans didn't take the bait. Four Japanese carriers at Midway were unaware that the Yorktown, Enterprise, and Hornet were lying in wait off Midway. The score: US lost 2 ships, 145 aircraft and 707 men, Japan lost all 4 aircraft carriers, nearly 300 planes, (they had no place to land) and over 2,400 men. US Admiral Nimitz declared that code breaking had provided a “priceless advantage” at Midway. The Japanese advance never regained its momentum.

The code breakers' third dramatic moment came when they decoded the detailed itinerary of Admiral Yamamoto's inspection trip of Japan's conquests. They learned the precise time his planes – two bombers and six escorting fighters – would leave the Japanese base at Rabaul. Sixteen US P-38s intercepted the Japanese over Bougainville and shot down both bombers. Admiral Yamamoto, commander of the attack on Pearl Harbor was later found dead in the jungle, “his white-gloved hand clutching his sword.” The girls in Washington had solved the code.

The war ended without Japan ever becoming aware that their “purple code” and several other military and diplomatic codes had been broken. Their ambassador to Hitler's Germany was a gold mine of information about German defenses on Europe's seacoast as D-Day approached.

It's not appropriate to exult now over enemy ships sunk, nor enemy soldiers killed; they had families who grieved, just as ours did. But for the millions of lives saved on both sides of the war because it ended when it did, we can honor the Code Girls.

Liza Mundy's book is a fascinating and detailed account of women who never spoke of their accomplishments until long after the war ended.

Reviewer's note: At one point 8,000 women were at work in US military cryptography, counting civilians, army (WACS), and navy (WAVES). I had a cousin, born about 1917 who spent part of her childhood in Japan ( her Dad worked for the YMCA there.) It never occurred to me to ask what she did in the WAVES, but with her experience of Japanese language, I now suspect she was one of those thousands.