21

Wet boots

In late September 1942, a signals unit arrived in Port Moresby on a troop ship from Townsville. The unit was the 55 Australian Special Wireless Group, with John ‘Jack’ Vasey as their commanding officer.

Port Moresby was the main Allied base in Papua New Guinea and the staging point for forward operations, such as the Diggers engaged in jungle warfare inland along the Kokoda Track.

The town had suffered numerous air raids, sometimes daily, from the Japanese army air force. The harbour was littered with the wrecks of bombed ships that jutted from the water like rusty islands. The beach was long, wide, and shallow — too shallow for swimming — but bomb craters filled with seawater made for good swimming holes. Most of the buildings in town were Port Moresby thatched huts, clustered around the central market, where the local currency was cowrie shells. Papua New Guinean tribespeople would visit the town, the men carrying spears, and the women carrying children slung in woven slings on their naked backs.

Arriving in Port Moresby in the dry season, it seemed to Central Bureau’s Doug Pyle that ‘everything was yellow’ — the grass, the earth, buildings, the occasional forlorn palm tree, and the skin of the soldiers taking Atebrin tablets to ward off malaria.1

By 21 September 1942, Imperial Japanese Army troops had reached the south side of the Owen Stanley Range, and were so close to Port Moresby that they could see its lights in the distance.

Australian troops had suffered heavy casualties fighting them along the Kokoda Track, in an extended battle to stop the Japanese overland advance to Port Moresby. Australian forces, including troops of the newly arrived 25th Brigade, had dug in on Imita Ridge. The troops of the Imperial Japanese Army, so close to their objective, were in a buoyant mood, and shelled the Australian defenders with heavy mortar bombardments.

Twenty-five miles away down on the coastline, Port Moresby had changed from a quiet colonial British outpost to a large Allied military base in an urgent and grim mood. Jeeps and trucks moved through the dirt streets.

The beach was contoured with bomb craters. The surrounding countryside was strewn with troop encampments, and landing fields were lined with the remnants of the Allied air force in the south-west Pacific.

General George C. Kenney, a new US army air force commander, had recently arrived from America to serve under MacArthur. Kenney learned that Allied air power in the south-west Pacific area — the combined number of planes of the Australian and US army air forces — totalled a paltry 80 aircraft. This wasn’t the fleet on the airstrips at Port Moresby, but the sum total for the entire of North Australia, New Guinea, and the south Pacific islands. Because of the focus on the war in Europe, much of what airpower the Allied nations had was deployed in Europe and Africa. Most of the rest had been shot out of the sky by Japanese Zero fighters or bombed by Japanese ‘Betty’ bombers as they sat on the grassy airstrips of northern Australia and southern New Guinea. Reinforcements were, of course, on their way from the United States.

Even for the operational planes in Port Moresby, air operations were a hit-and-miss matter, due to the extreme tropical weather of New Guinea. To the north, the towering Owen Stanley Range was an unbroken labyrinth of mountain ridges and jungle valleys, frequently covered with thick clouds and mist. Torrential rains frequently came over the far-northern side of the range, and would soon be coming to Port Moresby itself when the wet season began.

The signals unit did not stay in Port Moresby for long. They were taken by barge to their designated site on Fairfax Harbour to the west, at a place called Seven Mile. Their intercept site had already been set up, with antennas erected and radio receivers installed, thanks to two men who had arrived before them from 51 Wireless Group in Darwin.

The two operators from Darwin had been assigned to join Vasey’s unit to add much-needed experience and to bolster the unit’s numbers, which were currently at half strength.

Jack Butler, one of the two from Darwin, explained later how they had made the most of their early arrival:

When Gordon (my mate) and I were unloaded in Port Moresby nobody wanted to know us. The Japanese were advancing down the Kokoda Track and things were decidedly unpleasant for two unattached personnel. We made ourselves known to the area CSO and asked for a receiving set, aerial wire, stationery and a work tent so we could begin mapping out the Japanese groups in New Guinea. We did, of course, have an ulterior motive. We reckoned that, if there was to be another evacuation, we were going to be the CSO’s bag carriers.2

Jack and his mate, Gordon, operated the site on their own for four weeks before the arrival of Vasey’s 55 group. They had two kinds of radio receivers — the stock-standard American-made HROs, just like the ones in Townsville and Darwin, and an Australian model, the Kingsley 101, made in Melbourne. The HROs were normally reliable, but suffered in the damp, humid New Guinea weather. The Kingsleys were encased in rubber, making them more resilient in the jungle conditions and less likely to suffer damage in transportation.3

A direction-finding station was set up about two miles away. Enemy radio traffic was high, and the unit worked hard to keep up. There was a large amount of Japanese air activity; air raids against Port Moresby and other Allied bases were constant. The unit monitored army air-to-ground and naval air-to-ground traffic, and even in cases where they were not able to decrypt the message, alerted the local commanders whenever an air raid was imminent.4

The unit had two tents: one for interception, and one for intelligence. This was the structure for all the special signals units, including the 51 Section at Coomalie Creek, and 1 Wireless at Townsville (although they worked in a concrete bunker rather than tents). Wires connected the intercept aerials to the receivers in the intercept tent where the Kana operators worked, listening to Japanese Kana codes and transcribing them throughout the day and night. The transcriptions were then taken to the second tent for the intelligence staff to work on. The intelligence staff included personnel trained in decoding air-to-ground messages, a translator, and the commanding officer, who would make operational decisions about what to do with the intel gained from the intercepts.

Those in the intelligence tent were designated by Central Bureau as the ‘Y’ staff. The work of Y intelligence people was mysterious to the regular soldiers. They had been trained in intelligence, apparently, and probably thought they were better than everyone else. The regular signals personnel, in keeping with the Australian tendency to cut ‘tall poppies’ down to size, renamed them the ‘Shit Staff’.5 The name stuck.

A lot of air-to-ground messages that arrived on the desks of the Y staff at the camp at Fairfax Harbour were either partly encoded or not encoded at all. For example, sometimes the sender had composed the message using the codebook, but for whatever reason had done no further encryption, such as applying additives or scrambling the syllables using a cage. These secondary, more complex, techniques were called ‘encipherment’ (whereas merely using a codebook was called ‘encoding’). So, at Central Bureau, these partially encrypted messages were called unreciphered messages. And since the codebooks were often solved or mostly solved, such messages could be read on the spot by an experienced cryptanalyst.

On the other side of the mountains, at Wanigela on the north coast of Papua New Guinea, an advance party of four men from 55 Section had set up a direction-finding station. Just getting there had been an odyssey. When Jack Ryan had given them their orders back at the Bonegilla training camp, he had made four points:

1. You are going into enemy territory;

2. Never let your equipment be captured;

3. If attacked (on the way to location), retreat and go another way;

4. Best of luck.6

They went by ship to Port Moresby, from where they were flown to Milne Bay, and then travelled by ship 100 miles along the north coast to Collingwood Bay. There, they went ashore in a longboat, through the swamps to an Australian army camp at a small airstrip in a field of kunai grass.

They arrived with a single large tent, a Bren gun and ammunition, grenades, and two tons of direction-finding apparatus. They installed the direction-finding equipment, and, to protect it from the rain, constructed a hut out of natural material they found near the campsite. But the hut was no match for the tropical climate, and rapidly deteriorated. The jungle weather took a toll on the equipment, too, which had to be dried out in the sun periodically to kill the mould.

The basic principle in radio direction-finding — or ‘D/F’, as it was called — was to get two readings of the same radio signal from different locations, and use them to estimate the location of the source of the signal. When the D/F unit at Wanigela picked up the direction of an enemy radio transmission, and the D/F unit at the main base also got a fix on the direction from their location, the section could put the two together and estimate where the transmission came from.

Each day, Jack Vasey called the headquarters of the US army’s Fifth Air Force on a makeshift landline that ran from Seven Mile around Fairfax Bay to Port Moresby, giving them information on enemy aircraft movements, and particularly on incoming air raids. Sometimes the messages came in plain language that a local translator at 55 Section could read, and on those occasions Vasey could even give the commanding officer the intended target of the raid.

All messages and direction-finding readings were flown in mailbags back to Central Bureau, where they were sorted and processed by Pappy Clark’s traffic-analysis section. Here, insights were gleaned about the movements and plans of the enemy, particularly its troop movements up and down the northern New Guinea coast from places such as Palau and Rabaul. These insights were provided to Akin in a constant stream of updated intelligence, who in turn provided them to MacArthur and to MacArthur’s head of military intelligence, General Willoughby, whose disposition toward sigint was growing progressively warmer.

By the end of 1942, the Japanese army had retreated back across the Owen Stanley Range, and the data coming in from Wanigela was accordingly less useful with every passing week. It was getting to the point where most of the locations of the enemy transmissions were simply described as ‘a long way west’.

Vasey sent the order to Wanigela to pack up the D/F equipment and move to a new location. They moved out in early January 1943; but on the way out, the boat transporting them became beached in the mud, and was stranded there for two days. As they sat trapped in the shallow water of the bay, a Japanese reconnaissance plane flew overhead. They were now sure they were doomed, and anticipated a bomber would follow after the plane had spotted them. But apparently they were too small a target and too far away from the Japanese airstrips to bother with, because no bomber came.

After heading back around to Milne Bay and then to Port Moresby, they moved west to a place called Kerema, on the southern coast of New Guinea — just as remote as Wanigela had been — where they re-installed their D/F receivers and resumed their daily routine of mosquitoes, tinned food, and radio interception.