June 5th, 1944. An undisclosed location in southern England. The planned Allied invasion of Normandy has been delayed by weather, and by concerns over German troop deployments on the northern French coast. A grumpy American general is weighing all the options. A courier rushes in and hands him an urgent notification of a decrypted German message. The general reads it, and pauses while the surety of his decision comes over his face. He turns to his officers and says, “we go tomorrow.”
Dramatic enough for you? Well, you’ve probably guessed that the General was Dwight D. Eisenhower, making the final call to set the D-Day invasion in motion. And where did the decrypted message come from? Alan Turing, the British cryptographer and mathematician who everyone knows, and is famous today in Hollywood movies as the breaker of the secret German Enigma code?
No, the message came, essentially, from the cryptography team of Thomas Henry Flowers, better known as “Tommy,” the subject of our Man Crush Monday.
You see, even after Alan Turing and the massive Bletchley Park team cracked the Enigma code in 1941, the war of the codes continued. The Germans continually updated and improved Enigma, and created new codes and newer encoding methods that were even more complex than Enigma. It would be the height of understatement to say that their new machines and methods, especially the code called “Lorenz,” were more complicated and uncrackable than Enigma. In fact, cracking Lorenz would not only require more brain-power than had been devoted to cracking Enigma, it would require a new way of building machines that could handle and analyze such large volumes of data quickly.
Tommy Flowers was convinced he knew the answers to these problems. Flowers, the son of a bricklayer, had gone to night school at the University of London in the 1920s to earn a degree in mechanical engineering. He then worked for the research division of the General Post Office (the GPO) in Britain, especially on the problems of how to process enormous amounts of data and send it to its diverse recipients. The “Post Office” probably sounds very low-tech to most of you, but the British GPO also handled telegraph communication and, increasingly in the early decades of the 20th century, the telephone system. It was a colossal task trying to keep the data flowing, especially as it increased in volume, and the public expected it to move faster and faster as time went on.
In 1942, Tommy Flowers was drafted into the Bletchley Park team of engineers to help build machines to try to keep up with the advances in German military codes. It wasn’t just the fact that there were new codes. It’s that those codes were so much more complex that cracking them the way that the Enigma had been cracked took far too long. The British cracking machines had to be bigger and _much_ faster.
Flowers and his team proposed replacing the mechanical switches used at the time with a purely electronic method of working out code translation possibilities. You Buzzkillers who have seen the movie, The Imitation Game, saw a greatly simplified version of the machine that Alan Turing and the Bletchley Park team used to crack Enigma. Remember the “ca-chunk ca-chunk” sound it made when it was working? That was how it worked through the code possibilities using mechanical switches. Maybe the “ca-chunk ca-chunk” was a slightly over-the-top Hollywood sound effect, but it brings home the idea that this was mechanical process.
Flowers suggested using “valves” to take the load that the mechanical switches had been taking. “Valves” was the British term for what most Americans would call “vacuum tubes” or “electronic tubes,” like you used to see in old stereo sets. Little light bulb-looking things that controlled electric currents. String enough of these together, the Flowers’ team argued, and you could work through code possibilities many times faster than you could with mechanical switches.
But the Bletchley Park higher ups weren’t convinced. Not only would you need thousands of these tubes, but they seemed so flimsy in comparison to mechanical switches. The electricity passed through hair-like filaments, which would burn out (especially when the machines were turned off and then turned back on again). Flowers argued the Post Office’s systems already used thousands of these tubes, and that the key to making them last was to keep the machines on all the time. (This kept the tubes stable, apparently.) Again, his superiors were skeptical, but they allowed Flowers to keep working on his ideas on his own. He even spent a great deal of his own money building the machine he thought would keep up with German cryptography.
Well, Flowers and his team built that machine, and when tested, it proved to be 5 times faster than mechanically-based switching machines. It was brought to Bletchley in early 1944 and put to work on the new German Lorenz code. Nicknamed “Colossus” because of its enormous size, the machine immediately started cracking that code. But Flowers and his fellow engineers knew that they had to keep building faster machines with more capacity, and so they eventually built Colossus Mark 2, and it starting working on June 1st, 1944.
That’s right, June 1st, 1944. A hundred or so miles away, Allied commanders were fretting over two things that would affect the timing and destination of the Normandy invasion we know as D-Day. The first was the weather. Couldn’t do anything about that except rely on weather reports and forecasts. The second was reports of German troop movements in the coastal region of northern France. Hitler and his generals were expecting an Allied invasion of France, but they couldn’t decide where it was likely to be, and the German army was stretched somewhat thin in northern France. Hitler issued an order sending large numbers of troops to Normandy. Allied intelligence intercepted it, but nothing about that message or other intelligence about German troop movements indicated whether they were real, or whether they were a ruse or a feint to keep the Allies guessing about German troop strength in Normandy.
So in its first four days of operation, Colossus Mark 2 was already dealing with the most important messages of the war at that time. Where would the German army be? On June 5th, Tommy Flowers’ machine decoded German messages that showed that Hitler’s order to move more troops to Normandy was indeed a faint. The numbers of Germans defending the Normandy coast would be nowhere near what the Allied commanders had feared.
And so, Eisenhower issued that famous order – “we go tomorrow” – based on what Colossus was able to tell him.
The D-Day casualties on June 6th were bad enough, but they might have been much worse if that section of the Germans’ Fortress Europe had been defended fully.
Flowers and his engineering team built ten more Colossus machines before the war ended. And they were all needed to keep cracking German secret messages.
Electronic computers proved to be the future of computing, and most historians consider the Colossus the first programmable electronic computer. In recognition of his war work, the British government gave Tommy Flowers a £1,000 bonus. This wasn’t enough to reimburse him for what he had spent out of his own pocket to build Colossus. Rather than stuff the money in his bank account and chalk up the inadequate reimbursement to government cheapness, Tommy Flowers shared it with the fellow engineers and workers on his team.
We often complain about the “Great Man Theory of History” on this show. That is the idea that individual heroes are responsible for all the great things that have happened in the past. In a way, our Man Crush Monday and Woman Crush Wednesday shows fall into this trap. But it’s the work of people like Tommy Flowers, sharing what his reward with his co-workers that remind us how inadequate and insulting the Great Man Theory of History is.
Sure, we understand that Hollywood movies have to winnow down the number of characters involved when they produce a history-based movie like The Imitation Game. But, as I’m almost getting worn out saying, it’s up to us, Buzzkill Nation, to remember that great historical events are almost always the result of the work of dozens, hundreds, and in the case of Bletchley Park, thousands of people. And it’s up to us to recognize them, and remind the public that they were all Great Men and Great Women of history.
By sharing out the only tangible reward for his vital war work, that £1,000, Tommy Flowers did just that.
Jack Copeland, Colossus: The Secrets of Bletchley Park’s Codebreaking Computers (2006).