Review of 'The Emperor's Codes: Bletchley Park's role in breaking Japan's secret cyphers' by Michael Smith

Review by William W C Scott © 26 June 2022
Including a personal memoir of Donald Michie, Bletchley Park, at the end.

This book, entitled 'The Emperor's Codes' published by Bantam in 2000 is riveting and important.

Some of the revelations are astonishing and likely to be applicable even today.

Eg p21 'The record of the US Navy on co-operation, not just with the British but with their own Army, was not merely lamentable, it was shameful', p22 The existing literature credits this almost entirely to the US codebreakers. In fact, with the exception of Purple, only one of the key codes was broken by an American alone and that in Australia.

p29 'The British had been busy intercepting the diplomatic communications of their enemies, and on occasion their friends, since 1324 when King Edward II ordered that all letters coming from or going to parts beyond the seas be seized.'

p29 'The British Army was the first organization to realize the potential intelligence to be garnered from 'censoring' the German diplomatic communications sent on the cables of the international telegraph companies. The War Office set up a special section, MI1b, inside military intelligence, (Room 40) recruiting a number of eminent academics, a mixture of classicists and Egyptologists, to break the German codes. Shortly afterwards. the Royal Navy followed suit on the orders of Winston Churchill, then First Lord of the Admiralty.'

p30 After WWI 'The army and navy codebreaking organisations were combined into a single civilian operation of just twenty-five people based in London's Berkeley Square and known as the Government Code and Cipher School. First controlled by Admiral Hugh 'Quex' Sinclair, it was moved to Watergate House on The Strand and then to Queen's Gate, Kensington under Alistair Denniston, barely 5ft tall, an ex RN education officer who had run Room 40. Bletchley Park was bought and paid for by Sinclair in 1938, on his own initiative, as he understood the need for a secret place in the country 50 miles from London for codebreakers. Since two out of three cable companies were not British, a special clause requiring them all to hand over all traffic on their systems, in complete secrecy was necessary.p33 The first big test of Ernest Hobart-Hampden, GC&CS's Japanese expert, ex British Embassy, Tokyo and co-editor of the leading English Japanese dictionary, came with the 1921 Washington Conference of the nine major powers. The Japanese had emerged from WWI as the third largest naval power behind Britain and America. Cabled instructions from Tokyo were read by the codebreakers and the British and Americans got what they wanted.

p172 Japanese occupation of Midway, with its potential as a base for an attack on Hawaii, would leave the US Navy with little choice but to commit the bulk of the Pacific Fleet to a concerted counter-attack. p172 'The preparations for the Midway attack were being picked up by the codebreakers even before the Battle of the Coral Sea. There was frequent mention of a 'forthcoming campaign' in association with the cover designator AF, which Corregidor and Colombo realized was Midway as early as 7 March. Lt. Commander Joe Rochefort, head of the USN codebreakers at Pearl, agreed but Washington did not accept this, believing the thrust of the Japanese attack might be Hawaii, Alaska or even West Coast America.p173 By early May, both traffic analysis and deciphered JN25 messages indicated the massing of Japanese naval vessels in preparation for the impending operation in Saipan, the most logical base for an invasion of Midway or Hawaii. A message from Nagumo revealed that the Japanese proposed to stage their air attacks from a point fifty miles NW of 'MI', two days before the invasion. Hawaii, Melbourne and Colombo agreed Midway was the target. But Washington did not agree. So Rochefort and Holmes, a senior analyst, hit on a plan to prove it beyond doubt. p173 'Midway was ordered from Hawaii in a low-level code to report that its desalination plant had broken down and that it was short of fresh water, information of vital interest to a potential invasion force. On 22 May, Melbourne intercepted a message from Japanese naval intelligence reporting that 'AF' had radioed Hawaii that it had only enough water for two weeks. Thus AF had to be Midway. On the same day, Colombo reported intercepting a message from Japanese naval intelligence saying that the Japanese were planning to invade Midway. Rochefort had proved Washington wrong. He praised every member of his team at Pearl Harbor that broke the codes. p176 para 2 'Rochefort was able to brief Nimitz in full on the Japanese plans, giving the diversionary attack on the Aleutians on 3rd June. This was an extraordinary achievement in its own right. So detailed was Rochefort's version of Yamamoto's operational orders that Nimitz's staff could not believe it. But Nimitz was convinced and positioned his forces for a surprise attack. p176 para 4 'Us Navy dive-bombers from USS Enterprise and Yorktown, the carrier the Japanese believed they had sunk in the Battle of Coral Sea, were unleashed at 10.25 on 4th June, scoring immediate direct hits on the three Japanese carriers, Akagi, Kaga and Soryu. All three were sunk within five minutes.' p177 para 1 The sole remaining Japanese carrier, Hiryu, launched its aircraft against the Yorktown finally killing her off, but was itself left crippled and ablaze by dive-bombers from Enterprise. The Japanese were forced to scuttle it, leaving Yamamotu with no carriers or air support, forcing him to retire. The American codebreakers were highly praised by Nimitz for giving him a priceless advantage. Alas, it did not remain secret. Three days later a dispatch by the Chicago Tribune reporter revealed that the US Navy knew in advance all about the Jap Fleet. It was syndicated to several newspapers, notably, the Washington Times Herald. The reporter had been shown it by Commander Morton Seligman, Lexington's Executive Officer. Oddly, the Japanese did not believe their codes had been broken; rather that a codebook had been found or stolen or the Fleet movements worked out by traffic analysis.

Commander John Redman and his brother Admiral Joseph Redman, Director of Communications were determined to take charge of naval code breaking. [It had kudos, they wanted]. The former resented being made to look foolish by Rochefort over the Midway disagreement. Word was spread that the naval intelligence in Hawaii was not working well and Rochefort was to blame. Rochefort was eccentric, chain smoking, wore a dressing gown and rarely had time to take a bath. Obsessed, rightly with the codebreaking. Redman claimed that Rochefort was merely 'an ex Japanese -language student'. Rochefort was replaced and sent back to San Francisco to commission a new dry dock. A great waste of talent, as many thought, after the fact. Nimitz's recommendation for the DSM for Rochefort was twice denied, but given to political cronies of the Redmans. The DSM was belatedly awarded posthumously to Rochefort in 1986 p336.

p190 'The most notable feature of American- British co-operation was the inability pf the Americans to appreciate the full meaning of the word 'co-operation' The atmosphere was "What is yours is mine, and what is mine is my own." p276 The lack of US intelligence supply to CinC Eastern Fleet led the British to consider ditching the Americans on the Japanese side. .. while most of the material produced in Hawaii was swapped with Anderson, barely two fifths of that emanating from Washington found its way to Colombo. p238 By the spring of 1943, the British had become convinced that it was pointless if not foolhardy to rely on the Americans for Japanese naval material and were committed to building up their own codebreaking operations - both at Bletchley Park and in the Indian Ocean area - the Americans were holding back a large number of 'pinches', captured codebooks that would have been of immense use to the British codebreakers.

By their failure to pass on information to the British, many American lives were lost.

The itinerary of Admiral Yamamotu was available because of code messages to places he would visit being broken and available to Admiral Nimitz. Aircraft were sent from US Carriers to shoot down his plane.

p315 The US advance across the central Pacific had reached the strategically important Marianas Islands where Japanese naval messages intercepted in Hawaii and US ship-born radio intelligence units would prove vital. One, decoded at Pearl Harbor, revealed the exact location of Japanese submarines. A new hunter-killer destroyer group sunk five of the subs. Drawback: the Japanese realized it could only have come from signals and changed their procedures.

p316 Landings of US Marines on Saipan triggered the last large scale carrier battle of WW11. The Japanese 1st Mobile Fleet, including nine carriers [How many sunk? Unclear. Many, probably] aimed to squeeze the US 5th Fleet between itself and land-based air power on Guam. Radio intelligence on USS Indianapolis, Hornet and Yorktown, allowed US Navy aircraft to anticipate Japanese aerial attacks. Only one small group of 20 Japanese aircraft got through, the rest being shot down in a victory so overwhelming it became known as 'The Great Marianas Turkey Shoot.'

p318 The last big sea battle was at Leyte Gulf where RAAF was operational throughout and passed warnings of attacks to US air controllers as well as details of Japanese convoys reinforcing troops on Leyte. Signals from the convoy's aircraft intercepted sealed its fate. It was attacked by 347 US aircraft. All five troop transports and five escorting destroyers, including the Shimakaze, the fastest in the Japanese Fleet, were sunk. The only Japanese who survived had managed to swim ashore.

Fate of codebreakers?

  • p336-339 Frank Rowlett, US, broke The Purple cipher machine, one of the best achievements of the War: received US legion of merit and OBE.
  • John Tiltman, leading British codebreaker in Japanese codes who broke JN25 joined GCHQ until age 70, when transferred to NASA. OBE,1930, CBE 1944, US Legion of Merit 1946 Commander of the Order of St Michael and St George, 1954. Born 1894. Died Hawaii 1982. Offered a place at Oxford aged 13. Won MC in WW!. In 1933 he solved the Japanese military attache system which had been in use since 1927.
  • Hugh Alexander, chess champion, OBE, 1945, joined GCHQ. CBE 1955, Commander of St Michael and St George 1970. Died 1974.
  • Eric Nave, Australian codebreaker, OBE 1946, Died 1993.
  • Wilfrid Noyce was a member of the team that scaled Everest in 1953. Had broken the Water Transport Code in Delhi, at the same time as Joseph Richard of NASA, working alongside Tiltman. Noyce was killed climbing in the Pamir Mts, Soviet Central Asia, 1962.

A personal note: Around 1970, I was teaching at George Watson's College, Edinburgh, when a pupil of mine was the son of Professor Donald Michie, a genetics and cybernetics expert, soon with a chair in Strathclyde U. Michie came to see me at a parents evening about his son's progress. Michie had been a colleague of Alan Turing at Bletchley Park during WWII They were friends. I was told all about this, sitting in my classroom in front of my blackboard, Michie in the front desk. When Turing was awarded a prize of £2,000 for breaking the German Naval Codes (for six months, I think), they discussed what to do with the money [He could not be given a medal; the matter remained secret, rightly, for many years; few at Bletchley would know about it at the time]. It was, I think, early 1942 and the outcome of the war was uncertain. [Alamein was later] They decided to make two silver ingots of it [No point in using a bank that might become Nazi] and drive into the countryside and bury it. Michie had the car and they drove in the direction of Norfolk to a wooded area. Turing, alone, went off with the two ingots and dug a hole where he buried them, taking careful note of the place. After the war, Michie drove him back there, only to find that the woodland had been destroyed, the place having been used as a training ground or firing range. The cache could not be found. The solution Michie provided was a metal detector with which he eventually brought up the silver.

Michie later gave a public lecture at Edinburgh U. which I attended on the ideas of a Japanese about making what I remember as a 'creative computer'. Michie himself had done a lot of early work at Edinburgh on AI (still in a medical dept, too busy with ongoing research to bother to move) producing several tomes of programs, mostly simple programs, to perform specific tasks (nineteen volumes, it is said: I read bits of a few) to advance computer programming and bring computers closer to 'thinking machines'. The ideas of the Japanese were what he (in his paper) expected to occur; he had not arranged for their production. The lecture was given to clear up the wrong impression that Japanese were leading the research. Michie was doing that: his response to the Japanese paper.

What Michie told me about driving north to bury the silver in the ground in a wood is not reported by the science provided by the British Library which is unbelievable. Their idea that Turing would go around Bletchley Park hiding bars of silver is impossible: he would have been seen; it would have been found by others. What Michie told me has the necessary hallmarks of security, which was impressive at Bletchley, of vital importance. Michie and Turing were not stupid. They were among the ablest men of the age. The security among everyone involved at Bletchley continued long after the end of the war, because they were all systematically warned at the outset, on pain of death, to say nothing, in or out of Bletchley outside their own hut. [Smith describes a colleague who worked in the same section as Tiltman for two and a half years, yet who never at any time became aware of the genius class codebreaking success of his companion.] Long after the war ended, It was still the most secure establishment on the planet. Most of its workers died without uttering a syllable about it. In 1983 or thereby, I attended a talk at the Edinburgh Philosophical Society where a codebreaker first mentioned huge numbers used to protect secrets, a novelty because of the difficulty then of recognising very large primes. I was minutes secretary.

Contrast with the American experience: the first to blow trumpets of 'their' success, often someone else's, mindless of the fact that the enemy would read it and change their codes, causing great difficulty thereafter. That characteristic of Americans caused very many deaths to their own forces, as Michael Smith tells us. Still visible: Eg When Osama bin Laden was found in Afghanistan by the SAS, the Americans insisted on having the credit. By the time action was taken, Osama had fled the country. The SAS would have taken care of him immediately. Knowing this, they will doubtless, disobey orders and do the right thing in future. That should be a moral imperative, no matter the biggest force and the most money.

© William Scott, BA,BSc,MEd,FIMA,FSAScot