by Don Dennis
McKay concluded that it would be wise to find out exactly what was happening on Muschu. The best way would be to put in a reconnaissance patrol—men who could actually observe and report. Despite the best aerial cameras and the new electronic eavesdropping devices now in use, human observers were still the most reliable sources of information in a situation such as this. That would be a task for the Services Reconnaissance Department—a small unit of commandos also known as Z Special. They could get in, do the job, then get out again without the enemy even knowing they’d been there.
McKay had been involved with Z Special during his time with the South West Pacific Headquarters in Australia, when in September 1943, his department had helped gather information in preparation for Operation Jaywick. Using a captured Japanese fishing boat, the team had sailed from Darwin through Japanese-controlled waters to Malaya. There a raiding party paddled three canoes into Singapore Harbour, where they sank seven ships with limpet mines and then escaped without a casualty. Although this triumph had been hailed as justification of the special forces concept, Z Special’s true value had subsequently been found to be in the reconnaissance role. Z Special now had its South West Pacific headquarters with the Australian 1st Army in Lae, and an operational detachment at Aitape.
McKay took a file from a locked desk drawer and checked the Services Reconnaissance Department patrol schedule. Muschu had been listed several times since late 1944, but priorities kept changing and the patrols had been reassigned to other areas. It was still on the ‘to do’ list, but a definite time had not yet been allocated. He made a note to recommend to the G2 Operations that, in light of the guns sighting and other information indicating increased activity on the island, Muschu should be given priority for reconnaissance by a Z Special patrol.
3. ALLIED INTELLIGENCE BUREAU,
BRISBANE:
4 MARCH 1945
Tucked away in the basement of an old stone mansion in the suburb of Ascot Park, the No 1 Radio Intercept Unit was part of the intelligence network established by General Douglas MacArthur after the fall of the Philippines. Its existence known only to a few within the Allied Intelligence Bureau (AIB), the Radio Intercept Unit’s cryptographers deciphered Japanese transmissions recorded by listening stations scattered around the Pacific.
Like its British ‘Enigma’ counterpart at Bletchley Park in the UK, which deciphered German radio traffic, the Pacific radio intercept network had become a vital source of information for the Australian and American intelligence services. Although only small by comparison to the British operation, its capabilities were extensive, mostly due to the technology developed by the British early in the war. Once the Americans entered the war and learned the secret behind Britain’s electro-mechanical deciphering machines, they set about developing faster and more powerful equivalents. From an inconspicuous beginning in 1942, marred by rivalries between the Americans, Australians and British, by 1945 the AIB was capable of deciphering most high-level Japanese coded traffic within a matter of hours.
Apart from high-level ciphered traffic, radio messages were also being transmitted in lesser codes, down to operators at unit level who spoke in the clear. These conversations would usually be conducted using military jargon, containing information of little immediate value to an eavesdropping opponent. However, where possible, these conversations were also monitored by Allied listening stations around the Pacific, where they were recorded, then passed on for translation and analysis.
It is commonly perceived that only information originating from the highest sources—such as the enemy headquarters—is of value. However, even low-level messages contain clues that when viewed together by a skilled analyst build a picture that reveals the enemy’s intentions. Even information from the smallest unit is potentially valuable, so a great deal of effort went into monitoring what was known as the enemy’s ‘housekeeping’ radio traffic. Every military force relies on its logistic chain to keep it functioning—everything from ammunition to paper clips must be supplied where and when it’s needed. Deciphered, translated then classified, this administrative radio traffic, although mundane, continually added to the understanding of the enemy’s situation. Unfortunately for the AIB, hundreds—or even thousands—of such messages were intercepted by the network each day. To stay abreast of this barrage of information using human resources alone was a huge logistical task.
To speed the deciphering process, the US Signal Corps developed punch-card machines capable of sorting information according to pre-set conditions. The forerunner of programmable computers, these IBM tabulating machines filled every available space in the basement of the Ascot building, then overflowed into the mansion’s huge garage, with more machines installed in other buildings around the city. Even with the assistance of this new technology, the AIB’s effectiveness ultimately depended on the human factor. While tabulating machines were capable of sorting the translated information, they weren’t capable of recognising its meaning. That was left to specialists who would review the information, further categorise it, then direct it to Army, Navy or Air Force headquarters units, where local intelligence staff assessed how it fitted into their particular situation, then disseminated it further down the line. It was a continuous and often boring process, occasionally punctuated by a major event.
The Ascot Park building also housed eight area analysts, who scanned the categorised information to determine if it had any bearing on the areas they were assigned to monitor. This procedure, introduced early in 1943 to expedite the assessment process, had proven very successful. Six of these analysts were women, all respected by their male counterparts as exceptionally capable due to their uncanny memory and ability to discriminate between even the smallest of details.
On the morning of 4 March 1945, an hour after coming on duty, one of the women noticed an anomaly in the information she was reviewing. The night’s tabulator run had resulted in a thick sheaf of printed messages being delivered to her cubicle—mostly translations of administrative radio traffic transmitted between Japanese units around Wewak, an area she had been monitoring for six months. Such was the precision of her memory that she knew the order of battle of all units, their approximate strengths, and even most of their commanders’ names.
One series of messages contained a name she was familiar with, yet didn’t quite fit the context she expected. The first message read: ‘Order immediate recall of all 140 mm HE [High Explosive] ammunition from 14 Sempura battery. Have ready for transport by barge 2200 hours, 10th.’ Signed, Watanabe, Colonel.
There followed a reply from the artillery unit objecting to their ammunition being commandeered. It was signed Yusho, Captain, 14 Sempura.
Colonel Watanabe’s response came fifteen minutes later. ‘Report immediately to my HQ, Muschu.’
For a moment the duty analyst allowed herself to dwell on Captain Yusho’s predicament. The colonel sounded like a man not to be trifled with and Yusho would obviously face a severe dressing down for having questioned his order. However, her amusement was short lived as she realised something was out of place.
From a shelf she took down a directory of Japanese officers serving in New Guinea. This document was the result of an important intelligence breakthrough when, in late 1942, the capture of the Japanese Officer List by Australian Military Intelligence enabled the Allies to develop a detailed understanding of the command structure of the entire Japanese Army. Continually updated, it had been expanded to include the Japanese Navy and Air Force, with the career records and psychological profiles of most serving officers. Quickly flicking through to the name Watanabe, she saw that in the Wewak area there was one listing entered almost six months ago—but he was described as a lieutenant medical officer, not a colonel in command of an artillery unit.
During the past three months she had reviewed a number of messages originating from Watanabe, whom she deduced had been assigned to Muschu Island as the medical officer. From memory these were routine requests for supplies, health re
ports, manpower statistics—information a medical unit would be expected to provide its HQ on a regular basis.
But now Watanabe had revealed himself as a colonel. Even in the dwindling Japanese Army, promotion wasn’t that quick. Also, he was ordering artillery ammunition to be withdrawn from a combat unit—edicts certainly beyond the scope of a medical officer.
This anomaly suggested that there had been a mix-up with Watanabe’s original identification. Considering the amount of radio traffic the section dealt with, such errors were inevitable. The duty analyst made a note on a form advising of the possible error, put it in her out-tray, then returned her attention to the pile of printed messages.
It was almost midday when a file containing a list of updates from the duty analysts crossed the desk of the Second in Command of the Radio Intercept Unit, Lieutenant Commander David Mallory. Mallory made a point of reviewing the morning’s work, then over the lunchbreak he’d discuss any points of interest with the staff. That morning he saw, among other items, the correction to the identity of Lieutenant Watanabe originated by the Wewak area analyst. Another analyst in the ‘corrections group’ had confirmed the error, noting that it was caused by a simple spelling mistake. There were in fact two Japanese officers: Lieutenant Wantanabe of the medical corps, and Lieutenant Colonel Watanabe, a staff officer on the headquarters of the 21st Division in Wewak. The confusion of identities was understandable, caused by similarities in spelling and rank.
The note went on to explain that Lieutenant Colonel Watanabe was already known to the AIB. An artillery officer, he was a veteran of the Manchurian campaign, had served in the Philippines and had last been heard of in General Iwao Matsuda’s headquarters in January. The fact that he’d now shown up on the staff of the 21st Division in Wewak and had his own headquarters on Muschu Island posed some interesting questions.
Mallory was pleased to see that the error had come to light. Whether the information was important or not was best left up to the Sixth Division’s intelligence staff to decide. He drafted a signal instructing all information be forwarded immediately to Sixth Division Intelligence at Aitape.
4. ALLIED TRANSLATOR AND
INTERPRETER SERVICE, BRISBANE:
5 MARCH 1945
Located in the Brisbane suburb of Indooroopilly, the headquarters of the Allied Translator and Interpreter Service (ATIS) was housed in a large stone mansion with the tongue-twisting Scottish name of Tighnabruaich. A section within the Allied Intelligence Bureau, the ATIS had on staff more than 100 translators, most of them American-born Japanese sent to Australia for the duration. After training, many were posted to ATIS units attached to Australian and American forces throughout the Pacific, where they provided front-line translation services.
The Brisbane headquarters was also responsible for supplying translators to the Radio Intercept Unit and interrogating Japanese prisoners of war— mainly high-ranking personnel, or others suspected of possessing information of particular interest.
These prisoners would be flown to Brisbane from New Guinea or the Pacific Islands, then conveyed in secrecy to the mansion where the interrogation procedure began. For this purpose Tighnabruaich was perfect. Built in 1892 and modelled after a Scottish laird’s home and set in spacious grounds far from prying eyes, it was the type of building that chilled the imagination, with dozens of rooms, huge fireplaces, deep cellars and even hidden passages. Requisitioned by the military in 1942 and renamed Witton Barracks, it was guarded by a Military Police unit. Security was unobtrusive but tight, nearby civilian residents having no idea what transpired within the mansion’s thick stone walls—or that over 300 Japanese had been interrogated there by the end of the war.
The morning of 5 March 1945, an interrogation team had just completed a 24-hour session with a recently arrived prisoner and had gathered to compile their final report. The transcript would then be typed and forwarded to analysts in the Allied Intelligence Bureau for examination, cross-referencing and distribution.
The prisoner in question was a Japanese naval lieutenant captured after his submarine was attacked by US Navy aircraft off the island of Luzon in the Philippines only a few days earlier. Twenty survivors had escaped the crippled submarine, the remainder of the crew electing to die with their ship. Rescued by a destroyer, the survivors included a young lieutenant who was found to be the boat’s navigation officer. He was immediately separated from the rest of the crew, transferred to an aircraft carrier, then flown to the Philippines where he was blindfolded and loaded aboard a C-47 bound for Australia. Within 36 hours he was in the sterile surroundings of the Tighnabruaich ‘confessional’, being spoken to by friendly but firm Japanese men wearing American Army uniforms. The entire process was intended to disorient, confuse and intimidate. At this it was successful— the lieutenant conveyed almost his entire life’s story to the smiling gentlemen in khaki after only a few hours of persuasion.
What had prompted his urgent interrogation was mounting US Navy intelligence indicating that the Japanese were intending to launch a mass attack of submarines against elements of the Pacific Fleet. It was estimated that the Japanese could gather about 20 submarines and stage a suicidal assault—more a gesture than anything else, but a costly one for the Americans if it proved successful. The Japanese lieutenant’s vessel was suspected of being part of this assault.
However, the young lieutenant had a different story to tell. His submarine had been acting as a delivery service to the blockaded garrison at Wewak. Carrying twelve Long Lance torpedoes modified to hold cargo instead of explosives, they’d crept through the Allied naval patrols to within 10 nautical miles of the coast and launched all torpedoes on a track that beached them just south of the port. With each torpedo able to carry about 1000 kilograms, it was an expensive way of delivering supplies, but effective none the less.
When questioned as to what cargo the torpedoes were carrying, the lieutenant at first offered very little information. However, with gentle prompting, he did suddenly remember that his captain had at the last minute ordered him to supervise the placement of a small, well-wrapped parcel inside one of the torpedoes. What surprised the lieutenant was that the parcel contained two bottles of sake, addressed to a colonel whose name he clearly remembered as Watanabe. When coaxed, he was also able to give a rough description of what he saw in the torpedo’s cargo space. He described the compartment as being full, most of it taken up by one large cylindrical package marked ‘manufactured by Barr & Stroud’. The markings were in Japanese and English.
While this wasn’t considered new information—the Japanese had used this supply delivery technique in other blockaded areas of the Pacific—the ATIS interrogators realised that some elements might be important. It didn’t take long for ATIS staff to establish that Barr & Stroud was a Scottish engineering company that specialised in manufacturing precision military optical devices, including binoculars, telescopes and rangefinders. The Japanese Navy had purchased a large quantity of Barr & Stroud’s rangefinders in 1902, which they’d put to very effective use in the Russian–Japanese war of 1904. From the lieutenant’s description, the torpedo contained one of these early-model rangefinders, which although now obsolete, were still considered excellent instruments. A search through the department’s library came up with a catalogue of Barr & Stroud products, and from the known dimensions of the Long Lance torpedo’s warhead, as well as the Japanese lieutenant’s description of the package, it was deduced that the rangefinder was a model JA1901, a double-prismatic binocular instrument capable of resolving ranges up to 18,000 metres.
The two bottles of sake consigned to Colonel Watanabe gave a clue as to who the rangefinder was intended for. A check of the New Guinea Japanese forces personnel listing revealed that Watanabe’s record had been updated only a day earlier by the Allied Intelligence Bureau Radio Intercept Unit.
All this was duly noted, then forwarded to the Allied Intelligence Bureau HQ across the city in Queen Street. Within a few hours the report was being tr
ansmitted by encrypted radio to Sixth Division Intelligence in Aitape.
5. SIXTH DIVISION HQ, AITAPE:
6 MARCH 1945
Since the 2 March sighting of the guns on Muschu Island, daily sorties by reconnaissance aircraft had failed to confirm their location. Doubts were being expressed as to the validity of the original sighting: after a long search, one reconnaissance pilot reported seeing the charred trunks of two palm trees felled by naval gunfire that resembled gun barrels from certain angles.
Flight Sergeant Ron Smith, the pilot of the downed Beaufort, refused to accept that what he’d seen were palm trunks and, having recovered from a mild concussion, offered to fly as an observer in one of the reconnaissance aircraft. After cautiously recreating his last approach to the island several times, no guns were sighted. However, it was agreed that due to the heavy jungle canopy in the area, concealing two large guns from aerial reconnaissance would be relatively simple.
An Australian naval destroyer was called in to shell the high ground in an attempt to open up the canopy. After expending a hundred rounds of 105 mm ammunition with little effect on the foliage, the attempt was abandoned. Bombing the area by Beauforts using 120 kg bombs proved equally disappointing. By 5 March it was decided that perhaps the best course of action was to return to the original plan of dealing with the guns if they became active during the landings.