Enigma machines encrypted messages to protect their contents.
The German military used Enigma to encrypt communications. Polish, French and British cryptanalysts developed methods to recover its keys and read intercepted messages.
German engineer Arthur Scherbius files a patent for an electrical cipher machine, later developed into Enigma. His design uses a series of rotating wired wheels to transform each typed letter into another. The electrical path changes as the wheels turn.
1918 is the German application date, not the patent's publication. The illustration is explicitly a later US patent drawing, published in 1928.
Scherbius's company markets Enigma to the public, mainly for commercial and banking correspondence. The early Handelsmaschine uses four permanently installed cipher rotors and prints its output on paper.
No surviving Handelsmaschine is known. Older histories often call the early printing machines "Enigma A" and "B". This timeline follows revised archival research distinguishing the Handelsmaschine from the later A and B lamp machines. Model dimensions and finishes are inferred, and the demonstration uses a synthetic cipher.
Light bulbs above the two rows of keys display the output letters. This early version has two cipher rotors and a separate button to advance the mechanism.
No surviving specimen or authenticated wiring is known: case shape, materials and interior are reconstructed, with a synthetic reciprocal circuit and exhibit A–Z inserts for the originally blank, replaceable labels. November explicitly describes the manually settable third wheel later in 1924; August already gives a key such as R 15 22 and over 17,000 key-enciphering possibilities, leaving the Stockholm configuration uncertain.
An improved Enigma B is delivered to Sweden with three removable rotors and adjustable index rings. A ratchet and pawl mechanism advances the rotors when a key is pressed.
Three removable wheels, ring settings and automatic stepping. This Swedish version still uses an alphabetic, 28-character keyboard.
This model follows the surviving Enigma B Mark II A-133 delivered to Sweden on 6 April 1925, rather than the earlier two-rotor B offered in late 1924. Rotor I has letters; II and III have numbers 01–28. Its rotor and reflector permutations are published, but the entry-wheel wiring remains unverified and is assumed alphabetic here. Hidden dimensions and wire routes are reconstructed. The exhibit starts with I–II–III and rings A–01–01; physical thumbwheels change the starting positions.
Following earlier trials, the Reichsmarine orders 50 machines designated Funkschlüssel C (Radio Cipher C). This naval adaptation uses three of five supplied rotors, each with 28 contacts. Its 29 keys include Ä, Ö and Ü; X passes through without encryption.
Ten prototypes were ordered in December 1924, before the larger January 1926 order. This machine predates the M3 and has no military plugboard.
The Enigma D introduces QWERTZ keys and lamps, a hinged rotor cover, and a reflector adjustable to 26 positions. Of its four visible setting wheels, three are driven cipher rotors and one sets the reflector.
A settable reflector beside three rotors. There is no front plugboard.
The A27, later known as Enigma K, succeeds the D. Its turnover notch is attached to the adjustable index ring rather than the rotor body. This changes the relationship between the ring setting and rotor turnover.
In Britain, Hugh Foss analyses an acquired commercial A26. His work concerns commercial Enigma, which has no plugboard.
The name K appears from 1936, although A27 dates to 1927. This reconstruction follows Crypto Museum’s A818, dated to late 1927 or early 1928, with its published standard commercial wiring. Small dimensions and concealed wire routes are reconstructed; this is not a measured replica. The starting settings are I–II–III, rings AAA and reflector A. External power has no supply connected in this exhibit.
The German Army’s Enigma I enters service after several years of development. A plugboard on the front of the machine swaps pairs of letters as the current enters and leaves the rotors. Operators arrange three rotors, I, II and III, in any of six orders beside a fixed reflector.
The plugboard, fixed reflector and military wiring distinguish Enigma I from its commercial relatives.
Enigma I uses the Roman numeral I. It is distinct from the naval M1. This service date predates Hitler’s accession in 1933.
The compact G31 develops the counter-machine branch begun with the A28. A gear drive gives the rotors frequent turnovers and also moves the reflector. A counter records the number of letters typed. Often associated with the Abwehr, it also has other military customers.
Geared stepping, a moving reflector and a counter, without a plugboard. This is a separate branch, not an Army-wide replacement.
Hans-Thilo Schmidt sells secret Enigma documents to French intelligence. Gustave Bertrand’s cooperation with Poland brings operating information and keys to the Polish Cipher Bureau. The documents are valuable, but they do not reveal the internal rotor wiring.
Marian Rejewski reconstructs the military machine’s internal permutations using mathematics, intercepted messages and intelligence supplied through France. Together with Jerzy Różycki and Henryk Zygalski, he develops methods to recover its changing keys.
Cryptanalysts must continue recovering keys and adapting to changes in procedure. Later Allied work builds on the Polish methods.
Nazi rule and rearmament expand the military use of Enigma. The Luftwaffe adopts Enigma I, which the Army has used since 1930. The armed forces place larger orders as they expand.
This interval describes political change and expansion, not a claim that the Luftwaffe adopted Enigma on a specific date in 1933.
The M1 begins the naval family compatible with Enigma I. Naval equipment has lettered rotor rings and service-specific fittings. The M2 follows in 1938 and the M3 around 1939–1940. These variants differ in construction and operating procedures.
M1, M2 and M3 are sometimes grouped under “M3” in general accounts. The individual production variants should still be distinguished.
Reflector B replaces reflector A. Polish cryptanalysts have used a device called the cyclometer to catalogue the patterns produced by every rotor order and starting position. The new wiring makes the catalogue useless, and they must compile it again.
New reflector wiring, without another rotor position.
A changed German indicator procedure defeats the existing catalogue method. Polish responses include Zygalski’s perforated sheets and Rejewski’s electromechanical bomba, designed to exploit repetitions in message indicators.
The Polish bomba and the later British bombe are related parts of the history, but use different cryptanalytic designs.
The addition of rotors IV and V gives Army and Air Force operators five wheels to choose from. Three are still fitted at a time, but the possible orders rise from six to sixty, multiplying the work required of the Polish methods.
A larger selection of rotors, not a five-rotor machine.
The 3D collection uses the Army / Air Force’s numbered rims. Dimensions and finishes are reconstructed, and the display arrangement is not a historical storage box.
Naval wheels VI, VII and VIII enlarge the available set to eight. Each new wheel has two turnover notches, changing its stepping pattern. Three wheels are still installed.
Naval rims use A–Z, while Army and Air Force rims use 01–26: A corresponds to 01, B to 02, and Z to 26. The Navy used lettered rims before the 1939 expansion.
Additional naval rotors with two turnovers each.
Crypto Museum dates the additional naval wheels to 1939 and documents lettered rims on surviving M1 M522, manufactured in 1934. This does not establish an exact introduction date for alphabetic rings. The collection reconstructs dimensions and finishes but does not reproduce every service-specific ring-release fitting. Mathematical combinations do not establish which orders an operational key permitted.
At Pyry, outside Warsaw, Polish cryptanalysts explain their achievements to British and French representatives. They share their reconstruction of Enigma and methods for recovering its keys before the war begins.
After Germany invades Poland, Polish cryptanalysts continue their work in France, cooperating with French and British teams.
Britain’s Government Code and Cypher School builds its wartime operation at Bletchley Park. Alan Turing concentrates on naval Enigma, while interconnected teams attack different networks and turn intercepted radio traffic into intelligence.
The first British bombe, Victory, arrives in March. Turing’s design tests deductions from a guessed passage of plaintext—a crib. Gordon Welchman’s diagonal board makes the search more effective. The first bombe fitted with it, Agnus Dei, arrives in August.
Built by the British Tabulating Machine Company, bombes find candidate settings for further checking. They do not simply print a translation of every intercepted message.
Museum accounts disagree on the exact March arrival day, so the timeline uses the month. The photograph shows a modern reconstruction, not Victory itself.
The M3 production variant continues the naval line. It retains three moving cipher rotors, a reflector and a plugboard. Naval procedures and codebooks complicate cryptanalysis.
The separate full exhibit targets M3 specimen M2272. The history models share its detailed drive, with documented reconstruction limits, and demonstrate mechanics without encrypting a message.
The capture of U-110 yields naval cipher material, including indicator books. Weather-ship captures also supply keys. These documents help cryptanalysts decrypt naval messages.
A captured Enigma alone cannot provide access to every message. Current keys, codebooks, operating procedures and cryptanalysis are also needed.
The U-boat Triton network—Shark to Bletchley Park—switches to four-wheel operation. A thin extra rotor and thinner reflector fit into the naval machine’s existing width. The added wheel is set by hand and does not step while a message is typed.
The new arrangement and procedures interrupt Allied reading of this network. Access to other Enigma networks depends on their own keys and procedures.
A thin fourth rotor, set by hand, beside the three moving rotors.
1 February dates operational four-wheel use on this network, not a simultaneous replacement of every naval Enigma. The blackout extends into December, not just to the October capture.
British sailors recover codebooks from the sinking U-559. The material helps Bletchley Park attack Shark again. In December, recovered weather messages begin yielding useful U-boat positions for the Admiralty.
The capture on 30 October and the resumption of useful reading in December are different milestones. The recovery relied on both captured documents and cryptanalysis.
Joseph Desch’s team at NCR develops American four-rotor bombes for the US Navy. Their speed and growing numbers increase capacity to analyse U-boat traffic. Women of the US Navy’s WAVES help build and operate this machinery.
The Luftwaffe introduces UKW-D, whose internal connections can be rearranged in the field. Its use is limited, and older reflector systems remain in service alongside it.
Changeable reflector connections. No additional stepping rotor.
The Luftwaffe’s Enigma Uhr connects to the front plugboard. A forty-position switch changes the interconnection pattern. Bletchley Park encounters its traffic in July and solves the system within days.
An external plugboard accessory, not a clock driving the rotors.
By 1945, Bletchley Park employs nearly 10,000 people, roughly three quarters of them women. Interception, translation, indexing, traffic analysis, engineering and machine operation make cryptanalytic breakthroughs usable.
Enigma-derived intelligence contributes to Ultra, the closely protected intelligence supplied to Allied commanders. Not every key is recovered, and a message read too late may have little operational value.
Ultra is not a machine. Colossus attacked Lorenz teleprinter traffic, known at Bletchley Park as Tunny. It was a different cipher system, and Colossus did not replace the Enigma bombe.
Enigma remains in service after the defeat of Nazi Germany. In Norway, captured machines are adapted with new rotor and reflector wiring for police use. Other postwar users also retain machines.
Allied codebreaking remains largely secret after the war. Veterans cannot discuss their work, and historians lack access to the intelligence records. Later disclosures change accounts of wartime campaigns.
Władysław Kozaczuk publishes an account of the Polish contribution. David Kahn’s The Codebreakers also describes some wartime codebreaking. Both books precede the fuller public account of British Enigma work.
Bertrand’s book Enigma describes French intelligence cooperation and the Polish achievements. It appears before Winterbotham’s English-language account in 1974.
F. W. Winterbotham’s The Ultra Secret makes wartime Allied codebreaking widely known to English-language readers. The book reveals the scale of the intelligence operation to a wider audience.
Earlier Polish and French publications had already described parts of this work. Later records and research correct errors and omissions in Winterbotham’s account.
Karl Dönitz, the former commander of Germany’s U-boat force and later head of the Navy, learns the extent of Allied access to naval Enigma. Naval historian Jürgen Rohwer later describes his shock at the revelation.
This paraphrase follows a 1990 naval-history review reporting Rohwer’s account. No authenticated contemporary transcript has been established here, so no words are placed in Dönitz’s mouth. The portrait dates to April 1943, not the 1974 revelation.