The Invention

1918 · BerlinAn engineer with a big idea

The First World War has just ended. A German engineer named Arthur Scherbius — a clever, restless inventor with patents for everything from electric pillows to ceramic heaters — files a patent for a new kind of machine. It looks like a chunky typewriter in a wooden box. You press a letter, and a different letter lights up. Inside, spinning wheels change the scrambling with every single keystroke.

He calls it Enigma — from the Greek word for riddle.

1923–1926 · Nobody buys itA commercial flop

Scherbius tries to sell Enigma to banks and businesses: "Protect your telegrams from spying competitors!" There's just one problem — an Enigma costs about as much as a small car. Most companies shrug. Why pay that much to hide a message about wheat prices?

But one group is very interested. During the First World War, the British had secretly read Germany's coded messages — and Germany found out about it after the war, from the British themselves, who published books boasting about it. The German navy is embarrassed, furious, and determined that it will never happen again.

In 1926 the German navy starts using Enigma. The army follows in 1928, adding an extra scrambling layer of its own — the plugboard, a panel of sockets and cables on the front that swaps pairs of letters and makes the machine massively harder to crack.

Scherbius never sees what his machine becomes. He dies in 1929, after an accident with a horse-drawn carriage — an oddly old-fashioned end for a man who built the future of secrecy.

1933–1939 · RearmamentThe Nazis' favourite machine

When the Nazis take power in 1933, Germany secretly rebuilds its army, navy and air force — and all of them need to talk without being overheard. The military orders Enigmas by the tens of thousands. By the war's end, Germany has used roughly 40,000 of them: on ships, in submarines, in tanks, at command posts, even in weather stations.

Here's why they trusted it. To read an Enigma message you need to know exactly how the machine was set up: which wheels were inside, in which order, how each was turned, and which letters were cross-plugged on the front. The number of possible setups is absurd:

If you could test one setting every second, you'd need billions of times the age of the universe to try them all. The Germans did the math and relaxed: unbreakable. That confidence — as you'll read in File 02 — turned out to be their biggest mistake.

1939–1942 · In serviceA day in the life of an Enigma operator

Imagine you're a radio operator on a German U-boat (a submarine) in the Atlantic. Every month you receive a printed key sheet — a top-secret table listing the machine settings for each day, printed in ink that dissolves in water, so it can be destroyed in seconds if the boat is captured.

Each morning you set up your Enigma to match the day's row: choose the right wheels, set the rings, plug the cables. Your captain hands you a message — "convoy sighted, request permission to attack". You type it letter by letter. Each time you press a key, a lamp lights up; a crewmate writes down the lit letters. The result looks like total nonsense: XKQVR TZHFA…

That nonsense goes out by radio in Morse code. Anyone can hear it — British ships hear it, listening stations in England hear it. It doesn't matter. Without the day's settings, it's just noise. On another German boat, an operator with the same key sheet sets his machine the same way, types in the nonsense — and the real message lights up, letter by letter.