‘GHQ consistently belittled suggestions that this [Japanese] force could make any attack on Port Moresby and correspondents were encouraged to talk glibly about the “impassable barrier of the Owen Stanley Range”’
—Chester Wilmot, Australian war correspondent in New Guinea
Why did the Allied army fail to resist the Japanese landing on the Australian-mandated territory of Papua? It wasn’t for lack of knowledge. Allied High Command had been aware of Japan’s intentions for four months. They owed this intelligence to Ultra, the name for the Allied code-breaking system that had successfully cracked Japanese and German wireless codes.
The code-breakers were among the most brilliant cryptographers, mathematicians, linguists and computer experts in Britain, America and Australia.1 They worked day and night, deciphering signals using IBM punch card computers and the ‘Purple’ decoder, a mirror image of Japan’s secret diplomatic keyboard. General MacArthur treated this intelligence with the greatest respect; it usually formed the core of his strategic thinking.
As early as April 1942, a team of code-breakers working in a block of Art Deco flats in Melbourne had confirmed fears of a Japanese plan to capture Port Moresby—from the sea. Lieutenant Rudi Fabian’s Fleet Radio Unit Melbourne (FRUMEL)—one of two code-breaking units—managed to break the Japanese naval codes that warned of a seaborne attack on Port Moresby. FRUMEL sent the brief intelligence: ‘Suggest an early enemy offensive against Port Moresby before the end of April.’2
Not only did FRUMEL confirm this suggestion, on 4 May they calculated the precise route of the sea invasion. Immediately the American fleet steamed to the Coral Sea, and the first battle of aircraft carriers was joined. The Japanese were forced back, but not without the loss of one US carrier and a destroyer. The Battle of the Coral Sea was a qualified victory; FRUMEL even intercepted the Japanese wire that signalled defeat: ‘Moresby Occupation Force is to proceed [back] to Rabaul.’3
Allied intelligence had broken the Japanese navy’s codes; but what of the Japanese army? Could the code-breakers crack its strategy, too? A separate Allied decoding unit was established to decipher the army signals. These proved elusive; each word or phrase was embedded under a double layer of numeric codes. ‘The result was an apparently meaningless set of unconnected numbers.’4
Persistence yielded results. The Allies’ Combined Operational Intelligence Centre warned on 25 April of ‘an offensive move against the eastern New Guinea area before the end of the month…the major [Japanese] objective is to control the New Guinea–Torres Strait area involving the occupation of Port Moresby.’5 This didn’t mention an attack over the mountains, but the code-breakers were getting very warm. Then, on 19 May, they revealed the contents of a signal that said the Japanese army planned to invade Port Moresby via a mountain route from the north coast. One wireless section built up a detailed picture of the Japanese troops ‘attempting to cross the Owen Stanley Range’.6
In short, the cryptographers served up Japanese intentions to MacArthur on a platter.*
Even Australia’s conventional intelligence led High Command to conclude accurately, as early as 5 March, that Japan’s main object was to cut the air and shipping lines of communication between the United States and Australia.
Whoever controlled Port Moresby controlled Australia’s development as a base for offensive operations against Japan, so it would be natural for the Japanese ‘to attempt to eliminate Port Moresby or at least to neutralise it as early as possible’, said Allied GHQ.7 Their ‘best forecast’8 was that Japan would attack Darwin again in early April; Port Moresby in the middle of March; and the east coast of Australia in May. They erred only in predicting Port Moresby’s invasion three months too early.
Even if these warnings went unheeded, less scientific intelligence was shouting to be heard. Australia’s coastwatchers, a unit of extraordinarily brave men who constantly scrutinised the Papuan coast and Rabaul for signs of enemy activity, alerted Allied commanders to repeated sightings of Japanese ships in the Solomon Sea.9 ‘The Jap had beaten us to the punch,’ noted Eric Feldt, the coastwatchers’ commander, when Yokoyama landed.10
There were strong anecdotal warnings as well. Rabaul natives who deserted the Japanese after landing in Papua described the magnitude of loads they were expected to carry inland.
Why then did the Allies not respond to the overwhelming evidence of a Japanese attack? The answer is simple: MacArthur refused to believe that the Japanese would commit large forces to an overland invasion of Port Moresby. It was sheer folly, military madness. The Owen Stanleys—the central mountain range—formed an inviolable natural shield, he believed. MacArthur gainsaid his own intelligence sources. When Yokoyama’s men did in fact disembark, MacArthur dismissed them as a minor threat, ‘so deep-rooted was the belief in the effectiveness of the mountains as a barrier against invasion’.11
There was a related reason: MacArthur’s head of intelligence, Brigadier-General Charles Willoughby, persuaded his boss that the Japanese couldn’t possibly advance over the Owen Stanleys. The ill-advised Willoughby was still banging on about the impossibility of an overland attack—‘in view of logistics, poor communications and difficult terrain’12—as late as 12 August, days before the 10,000-strong Nankai Shitai landed at Buna.
Willoughby was neither a respected nor highly intelligent man, of whom MacArthur witheringly said, ‘there are three great intelligence officers in history and Willoughby is not one of them’.13 Nonetheless, Willoughby stayed by his boss’s side throughout the war, and exerted an influence on events that, with hindsight, seems remarkably disproportionate to the respect afforded his opinions at the time.
‘Willoughby got the intelligence wrong,’ concluded one military expert. ‘The Japs were landing large numbers of troops on the north coast. And Willoughby said they’re not coming far; they’re just coming a little way inland to build airfields.’14
There were no accurate maps of the area; people would land at Port Moresby with outdated Shell road maps. The press were tamed. War correspondents were told a tiny force of 2500 or less had landed and posed no threat. ‘GHQ consistently belittled suggestions,’ wrote the reporter Chester Wilmot, in one of his blistering critiques, ‘that this force could make any attack on Port Moresby and correspondents were encouraged to talk glibly about the “impassable barrier of the Owen Stanley Range”.’15
In any case, MacArthur’s mind dwelled on loftier stratagems than the Papuan sideline: chiefly his great northern offensive, the immediate goal of which was the recapture of the Philippines to whose people he had famously promised—after being forced to flee the archipelago—‘I shall return.’
He had one niggling concern, however: the little government station of Kokoda. No mountains stood in the way of the Japanese taking Kokoda, a strategically vital airfield situated on the northern foothills of the Owen Stanleys, a few days’ march from the sea. Certainly, the Allies couldn’t risk the loss of it; and in June this fear prompted MacArthur to wire Major-General Basil Morris in Port Moresby for details of his strategy to protect the vital Kokoda area.
Morris, the commander of Allied forces in New Guinea, didn’t have one. He answered that the Papuan Infantry Battalion was patrolling the area (actually many of the PIB had already deserted). His reply was the kind of lame assessment GHQ had come to expect from Morris who ‘readily admitted he had no pretensions to being a tactician’.16 But perhaps Morris, a fundamentally decent man, did not deserve one general’s description of him as ‘a very good scout—no brains but…stout-hearted’.17
At least Morris had his finger on the pulse of the problem (even if it was partly a problem of his own making). His troops were hardly trained at all and did not look forward with confidence to facing the enemy. It was something of an own goal, since Morris was ultimately responsible for training the odd assortment of misfits, drunks, rabble-rousers and looters who then made up Australia’s only defence against invasion.