How One Girl’s “CRAZY” Trick Broke ENIGMA and Sank 5 Warships in 1 Night – Took Down 2,303 Italians
March 25, 1941. At 9:23 a.m., 19-year-old Mavis Batty sat in a cold, dimly lit room at Bletchley Park, the heart of British codebreaking efforts during World War II. The air was frigid, and she could see her breath as she stared at an encrypted Italian naval message. The weight of the world seemed to rest on her shoulders. If she couldn’t decode this message within the next 72 hours, thousands of British sailors would pay the ultimate price in the Mediterranean.
Mavis was a university dropout, having left her studies just six months earlier to join the war effort. She had no experience breaking codes and had yet to crack a single Enigma message. Yet, here she was, facing a daunting task that had stumped the best cryptographers in Britain for 18 months. The Italian naval Enigma was notorious for its complexity, with daily key changes and billions of possible combinations. The British Royal Navy was desperate; Mussolini’s fleet was wreaking havoc on supply convoys to Egypt, sinking ships faster than they could be replaced. February had seen seven British cargo ships torpedoed, resulting in 340 sailors drowned. March was proving even worse, with nine ships lost and 450 sailors dead..
As Mavis sifted through the stacks of encrypted messages, each one representing a potential intelligence failure, she felt the crushing pressure of time. The General Wavell in Cairo was running out of essential supplies, and if the convoys didn’t get through, Britain would lose its foothold in North Africa. The stakes couldn’t be higher.
Suddenly, a breakthrough came. After 36 minutes of scrutinizing the gibberish before her, Mavis spotted something unusual: a repeated pattern in the encrypted text. The six letters “sqppbn” appeared at two different positions in the message. This was extraordinary. The Enigma machine was designed to ensure that the same plaintext would never encrypt to the same ciphertext. The odds of this happening were astronomically low—billions to one—unless the Italian operator had typed the same word twice at precisely the right rotor positions.
Mavis’s heart raced. Was it possible that this operator had been lazy? Could he have used the same filler word repeatedly? If she was correct, these identical patterns represented the same plaintext word. This was the opening she needed.
Her intuition had been honed from an early age. Growing up in Dulwich, South London, Mavis had always seen patterns where others did not. She had a knack for word games and crossword puzzles, solving them faster than anyone in her family. Her professors had recognized her gift for linguistic patterns, and when war broke out, she wanted to contribute meaningfully. A recommendation from her German professor led her to Bletchley Park, where she was assigned to the research section led by Dilly Knox, a legendary codebreaker.
Knox was eccentric and brilliant, having cracked codes for decades, but he was also dying from stomach cancer. He needed results quickly, and Mavis felt the urgency of his situation. Despite being ordered to stop work on the Italian Enigma, Knox continued in secret, believing that the Italian operators would eventually make a mistake. Mavis understood the risks involved; if she failed, it could cost them their jobs, or worse, their lives.
With a sense of urgency, Mavis approached Knox, showing him the repeated pattern and explaining her theory about the filler words. Knox’s expression was unreadable, but after a tense moment, he smiled—the first time she had seen him do so in weeks. “Prove it works,” he instructed, giving her the green light to pursue her hunch.
Mavis dove into the task, working through lunch and skipping breaks. She knew she had to identify the filler word without the daily Enigma key. After hours of calculations and testing various common Italian words, she remembered that Italian operators often used the word “perks” as a filler. It was a generic term, meaning “for” or “to,” and she hypothesized that both occurrences of the repeated pattern could represent this word.
If she was right, she could reverse-engineer the Enigma settings. She worked tirelessly, calculating rotor settings and plugboard configurations until, at 6:47 p.m., she felt she had it. Exhausted but exhilarated, she presented her findings to Knox. He took three minutes to review her calculations, then nodded, acknowledging the potential significance of her work.
They needed to verify the settings using a captured Italian Enigma machine. Knox retrieved the machine from his office, and as he configured it according to Mavis’s calculations, she held her breath. The machine clacked and whirred, and as the output lamps flickered to life, clean Italian plaintext emerged. Mavis read the first line, her heart racing: “Fleet attack. Creet. March 27.” They had broken the Italian naval Enigma.
The decoded message revealed that the Italian Supermarina was ordering Admiral Angelo Ecino to deploy his entire battle fleet—three heavy cruisers, two destroyers, and air cover—against British convoys near Crete, scheduled for departure on March 27 at 1800 hours. This was a major ambush, and without Mavis’s breakthrough, British ships would have sailed straight into danger.
Knox sent the intelligence directly to Admiral Sir Andrew Cunningham, the commander of the British Mediterranean Fleet. Cunningham received the decoded messages at 7:30 p.m., and after reading them twice, he began planning a counter-strategy. He needed to deceive the Italians into thinking that the British fleet was unaware of their impending attack.
On March 27, Cunningham played golf at the Alexandria Sporting Club, ensuring he was seen as relaxed and casual, not a man preparing for battle. He instructed his staff to deliver his luggage to his residence publicly, creating the illusion that he would spend the night ashore. Under the cover of darkness, however, he quietly boarded his flagship, HMS Warspite, and prepared his fleet for an ambush.
The British fleet set sail at 7:30 p.m., heading northwest toward the Italian fleet’s expected position. Mavis worked around the clock, decoding more messages and providing Cunningham with vital information about the Italian fleet’s movements. As the Italians set out to intercept the British convoys, they had no idea that they were sailing into a carefully laid trap.
On March 28 at 8:12 a.m., British aircraft from HMS Formidable spotted the Italian fleet 70 miles south of Crete. The Italians, realizing they had been detected, attempted to turn back. But Cunningham’s fleet had positioned itself directly between the Italians and safety. At 10:30 a.m., British torpedo bombers launched an attack, and despite suffering losses, one torpedo struck the flagship, the Vittorio Veneto, crippling it.
In the chaos that ensued, the Italian fleet scattered. Admiral Yachino ordered his cruisers to form a protective screen around the damaged flagship, but it was too late. The British battleships, positioned just two miles away, unleashed a devastating barrage. The Italian cruisers Fiume and Zara were obliterated in minutes, with heavy casualties among their crews.
As the battle raged on, the British destroyers launched torpedoes at the remaining Italian vessels, sinking them one by one. By the end of the engagement, 2,303 Italian sailors had lost their lives, while the British suffered minimal casualties. The Battle of Cape Matapan became one of the most one-sided naval engagements in modern history, and it all stemmed from Mavis Batty’s keen observation of a repeated filler word in an encrypted message.
The aftermath of the battle was grim. Thousands of Italian sailors were left drowning in the Mediterranean, and the British destroyers could only rescue a fraction of them before being forced to withdraw due to the threat of German aircraft. The Mediterranean supply line remained open, allowing British forces in North Africa to receive the supplies they desperately needed.
Mavis’s actions had not only saved her brother Jeffrey’s life—who was serving in the Royal Navy—but also ensured the success of British operations in North Africa. Her intuition and ability to spot patterns had changed the course of the war.
For years, Mavis continued her work at Bletchley Park, breaking multiple Enigma variants and training other cryptanalysts. She became one of Knox’s most trusted analysts, and when he died in 1943, she was one of the few he personally requested to continue his work. However, the Official Secrets Act prevented her from sharing her story, and she lived a quiet life after the war, becoming a garden historian and raising a family.
It wasn’t until decades later that Mavis’s contributions began to gain recognition. In 1974, the British government partially declassified Bletchley Park operations, and historians started to uncover her significant role in breaking the Italian Enigma. Despite being overshadowed by figures like Alan Turing, Mavis Batty’s story is a testament to the power of intuition and the critical importance of every individual in the war effort.
Mavis Batty passed away on November 12, 2013, at the age of 92. Her obituary in the Telegraph described her as one of the most important female codebreakers of World War II, but many still remain unaware of her contributions. Without her keen eye and determination, the outcome of the Mediterranean campaign could have been drastically different.
The story of Mavis Batty serves as a powerful reminder that intelligence work in war is not solely about brilliant mathematicians or advanced technology. It is also about the human element—individuals who notice the small mistakes that can lead to significant outcomes. Mavis’s legacy lives on, not just in the history of codebreaking but in the lives she saved and the impact she had on the course of history.
