[Music] during the deadliest war in history Britain and the Allies stand against the Axis powers nazi Germany has unleashed a new kind of warfare swift dynamic and merciless it's coordinated by radio communication sent in sophisticated codes which the German high command believed to be unbreakable but far from the front lines in a quiet corner of England a secret operation is underway thanks to brilliant minds cuttingedge technology and tireless persistence the communications of the Axis powers are being revealed generating intelligence that could win the war for the Allies these secrets are protected by the highest security classification Ultra 1939 europe is on the brink of war since seizing power Adolf Hitler and his Nazi party have dismantled Germany's democratic institutions and rapidly expanded its armed forces in preparation for a war of conquest radio will be the backbone of military communication in the coming conflict and in wartime every message must be carefully encrypted using secret codes if you can break your enemy's wartime codes you can see the composition and condition of their forces and gain early warning of impending attacks throughout the 1930s British codereakers have been studying German encryption methods with limited success but they are about to be granted a breakthrough [Music] somewhere in the Pere forest outside Warsaw a secret meeting is taking place between the intelligence services of France Britain and Poland referring to themselves as X Y and Zed the three nations have been working to break German codes among the British party is Dilly Knox a brilliant and eccentric academic who's one of Britain's foremost cryp analysts his scholarly research had focused on reconstructing complex Greek poetry from tiny fragments of ancient papyrus like his counterparts in the French and Polish intelligence services Nox's focus is the cipher machine used by the German military [Music] a device that's small and portable yet generates codes that might be unbreakable it's called Enigma in the field its operation is straightforward a message is typed on the keyboard and with each key press the operator notes down the letter illuminated on the lamp panel above these letters are transmitted by radio in Morse code and at the receiving end they're typed into an Enigma machine with precisely the same settings the illuminated letters on the lamp panel will reveal the original message but which letter lights up to each keystroke is determined by a tangle of electrical connections within three rotors that shift with every key press each rotor's internal wiring is unique and they can be rearranged to create new electrical pathways as a final layer of security a plug board at the front of the machine swaps letters in pairs it has 150 million million possible configurations although Dilly Nox understands how Enigma works in principle he needs to know how the machine is wired internally he's hoping for answers from the polls poland is facing the imminent threat of German invasion and they are willing to share knowledge in exchange for support from France and Britain what they reveal at this meeting will finally unlock the secrets of Enigma the story of the Polish breakthrough begins in 1931 when a German named Hans Tilos Schmidt walks into the French embassy in Berlin he offers stolen German cryptographic secrets in exchange for cash his offer is accepted among the documents he provides code books and detailed operating instructions for Enigma the French and British intelligence services aren't convinced it's enough to break the Enigma code but the Poles are far more concerned about a possible future conflict with Germany they accept the documents and hand them to three brilliant mathematicians Henrik Zigalski Yi Rojiski and Marian Ryfski ryfski achieves the most remarkable breakthrough astonishingly with only the incomplete information from Hans Tilos Schmidt he reduces the Enigma's operation to a series of mathematical equations and reconstructs the machine's internal wiring with Ryfki's breakthrough Poland is able to break Enigma messages as early as 1933 and by 1938 they are breaking 75% of intercepted Enigma communications but their success comes to a sudden halt as German rearmament gathers pace its military tightens Enigma procedures and introduces two new rotors these rotors can be swapped with the existing three in 60 possible combinations this massive increase in complexity means Poland can no longer read Enigma traffic and now with a German attack seemingly imminent they decide to share their Enigma research an astonished Dilly Knox gratefully accepts the information provided by the Poles britain is now armed with the intelligence it needs to begin the fight against Enigma and preparations have already begun [Music] something strange is happening in the small English town of Bletchley just north of London at the old mana house on the outskirts of town workers are pouring concrete installing new telephone cables and hooking up power lines meanwhile a collection of eccentric academics is starting to arrive the purpose of their visit is a state secret they are codereakers from the Government Code and Cipher School or GCNCS and they are tasked with breaking the secret codes of Britain's wartime enemies with war seemingly imminent Captain William Ridley chief administrative officer of the Foreign Intelligence Service has organized an evacuation of Britain's codereakers to the Mana House at Bletchley the site is out of the way of potential German bombing raids but well connected by telephone and rail the operation will become known as Captain Ridley's shooting party the Mana House will serve as a wartime home for GCNCS but the head of the organization Commander Alistister Denniston has another problem to solve denniston is in charge because of his codereing work in World War I his modest calm demeanor works well to keep his sometimes eccentric staff in line at this time GCNCS has around 150 staff working in a relaxed and academic atmosphere the staff affectionately nickname it the Golf Club and Cheese Society but if war breaks out they will receive mountains of intercepted communications and will have to turn codereing into an industrial operation denniston begins a search for what he calls men of the professor type and he doesn't have to look far from Bletchley Park oxford is to the west and Cambridge to the east the university is a fertile ground for recruitment amongst his early recruits are two mathematicians gordon Welshman a brilliant codereaker whose ideas will revolutionize methods at Bletchley Park and Alan Turing a genius whose work at Bletchley will lead to huge advancements in the fledgling field of computer science gcncs now has a base of operations and a list of potential staff ready for the outbreak of war but in 1938 the further appeasement of Hitler by the Munich Agreement removes the imminent threat of conflict the men and women of Captain Ridley's shooting party go back to their regular London offices they would return to Bletchley one year later [Music] britain is at war the nation mobilizes young men are called up for military service older men and women take jobs in factories those outside the cities prepare to take in evacuee children meanwhile GCNCS makes its official move to Bletchley Park the flood of intercepted German messages begins to arrive the pressure is on intercepting enemy communications is the job of outposts called Y stations dotted around the British Isles and colonies here radio operators scan the airwaves for the staccato pulses of German military traffic it's delicate work signals can drift across the spectrum be distorted by weather or be buried under other radio signals using the same frequency from the Y stations messages are sent to Bletchley for analysis but there's more than one enigma code to break the German Army Navy and Air Force use a variety of separate networks each using different settings for their Enigma machines each network must be broken individually they're given color codes army traffic is green red and brown for the Air Force eventually there'll be so many networks that the codereakers run out of colors and start to use the names of animals insects and [Music] [Music] plants in its early days Bletchley Park is chronically understaffed and overcrowded codereakers work 24 hours a day in shifts the operation quickly outgrows the mana house and much of the work is moved to hastily assembled out buildings in the grounds the huts as they are known are very basic with hard concrete and wood floors bare light bulbs and windows that are blacked out at night at first codereing is done by hand with pencils and squared paper it's exhausting work that requires sustained mental effort and as much patience and concentration as brain power the first methods to break Enigma are inherited from Polish code breakers who had discovered a critical security flaw in the German military's procedures each day Enigma operators are given instructions on which rotors to use and in what order each rotor's inner wiring is also offset with an external ring this is known as the ring setting then they follow instructions on how to wire the plug board finally the operator chooses a starting position for the rotors which must be unique for each message this is known as the message setting this message setting must be sent to the recipient so they can decode the incoming message but without broadcasting it to enemy eavesdroppers to do this the operator encrypts the message setting using the Enigma machine itself they set the rotors to a starting position known as the ground setting next they key in their unique three-letter message setting finally they set their rotors to the message setting and type the message but to guard against radio interference German protocol dictates that the message setting be typed in twice this is the critical security flaw the polls have identified it means allied codereers can get two sets of three letters that they know must have been identical before encoding the repetition of an identical group of letters gives them a way in to the Enigma code in January 1940 Bletchley breaks Enigma for the first time cracking the daily settings for the Air Force and Army Enigma british codereakers are reading military orders and reports in almost real time it's an astonishing intelligence coup and the Germans have no idea it's happened but just 4 months later the Germans unexpectedly tighten security and change their procedures overnight many techniques inherited from Polish codereakers become useless bletchley Park is blind once more just as Hitler prepares to launch a devastating new [Music] offensive as fighting rages in France one of Bletchley Park's newest recruits provides a breakthrough 21-year-old mathematician John Heravel had only just joined the operation when he had a flash of inspiration perhaps the way into Enigma isn't through any cryptographic weakness but through human error aravel put himself in the mind of an Enigma operator starting a shift at dawn and being ordered to rush off an important message after setting up their machine an operator who was tired stressed or just lazy might not randomize the rotor positions before sending their message this meant that the starting rotor position might be the same or close to the ring setting heravel's insight gives the codereers a way back into Enigma on the 22nd of May they use Heravel's techniques to break the Luftvafers Enigma traffic cenamed red this network stays broken for most of the [Music] conflict but no codereaking success can compensate for the fact that the Allies are clearly losing the war [Music] britain faces its darkest hour of the war on the 16th of July 1940 Hitler issues directive number 16 calling for the development of invasion plans for the British Isles but before that can happen Germany will have to knock out Britain's air defenses that summer the German Luftvafer battles the Royal Air Force in the skies over southern England the RAF has several advantages not least that thanks to Bletchley Park Hut 6 the British are reading the Luftvafa's Enigma traffic the RAF gets advanced notice of German flight paths and targets allowing it to ambush enemy bombers and giving those on the ground some warning of an incoming raid it also allows the British to jam and disrupt German navigational signals for their bombers sending them off course the Luftvafa is defeated [Music] but though the threat of invasion has passed Britain's position remains perilous hitler dominates the continent the USA refuses to be dragged into the conflict the Soviets have made their own pact with Germany and the British face another crisis at sea German yubot prey on ships carrying vital supplies to Britain the Battle of the Atlantic has the potential to be the decisive conflict of the war breaking German naval codes will become a top priority for Bletchley Park in a race to save the convoys and save Britain [Music] in World War II intercepting messages and cracking encryption was a painstaking process gathering personal information about a specific individual could be very hard indeed but in the internet age that's not necessarily the case our digital footprints are only getting bigger and if we're not careful our personal information can easily fall into the wrong hands did you know that your personal identifiable information or PII is collected and sold online by data brokers they crawl the web to gather your information build a profile of you and then sell it on to other organizations this means that anyone can buy your PII without your knowledge fortunately our video sponsor Delete Me offers a range of tools to manage your online presence with Delete Me you can easily find and remove your personal information from the internet you simply tell them what information you want deleted and 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five-star reviews you know you can trust the industry leader in online personal data removal so to safeguard your personal information in the digital age head to jointdeiteme.com/epic history a huge thank you to the Bletchley Park Trust for their support in making this video step into history and discover the incredible achievements of the people who worked at Bletchley Park during World War II once the top secret home of Britain's World War II codereat breakers Bletchley Park played a vital role in the Allied war effort today Bletchley Park is a museum and heritage site opened daily to visitors and full of immersive exhibitions restored historic buildings and hands-on displays walk in the footsteps of the Enigma codereers explore the ingenuity behind the bomb machines and get a closer look at how intelligence was gathered processed and used you might even discover you have what it takes to be an intelligence officer yourself learn more and book your visit at fledgelypark.org.uk or click the link in our video description [Music] thanks as always to the Patreon supporters who helped to make this channel possible from builders such as Michael Javier Valenuela and Michael Morali to citizens like Ying Nam Fong Abdul Rahan and the Haunted Fish and heroes like Ted Vinachci join their ranks by joining us on Patreon where you'll get early adree access to new videos exclusive updates and votes on future video [Music] topics heat heat [Music]