Operation Broadaxe

This was the Allied deception plan to persuade the Japanese in mid-1945 that the next major Allied offensive would not fall on the Japanese home islands (June/August 1945).

As such, ‘Broadaxe’ was the overall plan for Pacific deception 1945, and was designed to persuade the Japanese not to move troops to their home islands, and to deploy those troops already on the home islands to meet ‘threats’ distant from the planned ‘Olympic’ invasion of Kyushu islands. The ‘story’ promulgated by ‘Broadaxe’ was that their was to be no invasion of Japan until the Allies had taken additional bases, and therefore that the Allies’ next objectives were Formosa, the Chinese coast, Thailand, French Indo-China, Sumatra, the Kurile islands group, and Hokkaido island at the north of the home islands where the garrison comprised only the five divisions of Lieutenant General Kiichiro Higuchi’s 5th Area Army.

Related operations were ‘Pastel I’, ‘Pastel II’ and ‘Conscious’.

‘Broadaxe’ was formally approved on 15 June 1945 by the Combined Chiefs-of-Staff and issued on the following day. The plan’s objectives were to persuade the Japanese to redeploy no ground forces from the mainland of Asia to the home islands; to disperse their ground forces already in the home islands to defend northern Honshu and Hokkaido (held by the six infantry divisions of Lieutenant General Teiichi Yoshimoto’s 11th Area Army and five divisions of Higuchi’s 5th Area Army respectively) as the real ‘Olympic’ invasion would come at the other end of the archipelago in Kyushu island; to commit all available sea and air forces against Allied naval and air attacks on the home islands so they could be destroyed before the invasion; and to misinterpret Allied intentions with regard to operations in Borneo, Malaya, China and the Kurile islands group. The ‘story’ which would thus be promulgated would be that the Allies understood that an invasion of Japan would be very costly, could not be undertaken until a long period of naval blockade and saturation bombing had seriously weakened the Japanese on the home islands, and would in itself probably not end the war as the Japanese would plan to withdraw to the mainland of Asia and continue the struggle there. Accordingly, the Allies come to the conclusion that Japan must be encircled before an invasion was attempted, that additional heavy bomber bases created close to Japan, and that there must be a build-up in the Aleutian islands group for operations against Hokkaido. In addition, there would be landings on the Chinese coast as early as possible to help keep China in the war, and political pressure required the liberation of British, French and Dutch territories as soon as possible.

The notional Allied strategy thus suggested was the seizure of additional bases for saturation air bombardment; an early amphibious assault on Formosa late in the summer of 1945 as a preliminary to landings on the Chinese coast; a build-up in the Aleutian islands group in preparation for operations against Hokkaido in the autumn of 1945 to gain additional nearby air and sea bases; an acceleration of the tempo and quantity of supply deliveries to China to enable Generalissimo Chiang Kai-shel to intensify Chinese Nationalist activities in the interior of China with the objective of drawing Japanese strength away from areas of Allied landings on the China coast; an amphibious assault from the Philippine islands group against French Indo-China in the autumn of 1945 in co-ordination with an overland assault by Chinese Nationalist forces from the north and in conjunction with a British invasion of Thailand; an assault on the island Sumatra from India late in the autumn of 1945; and an advance into the Yellow Sea in the winter of 1945/46 to secure bases for air and inland operations.

Within this scheme, Admiral Chester W. Nimitz and General Douglas MacArthur, as commanders-in-chief of the US Navy and US Army forces in the Pacific theatre, were to be responsible for generating the threat to Formosa and the advance into the Yellow Sea, Nimitz in collaboration with the Alaskan Department was to be responsible for the notional build-up in the Aleutian islands group; MacArthur in collaboration with Admiral the Lord Louis Mountbatten and Lieutenant General Albert C. Wedemeyer, the British and US commanders in South-East Asia and China, would be responsible for the threatened Indo-China landing; Mountbatten in collaboration with Lieutenant General Daniel I. Sultan, the US commander of the India-Burma Theater of Operations, would be responsible for the assault on Sumatra; Sultan in collaboration with Wedemeyer and Mountbatten would be responsible for the apparent acceleration of supply to China, and Wedemeyer would be responsible for intensifying activities in the interior of China to divert Japanese forces and aid the Indo-China project. Major General Curtiss E. LeMay’s (from 2 August Lieutenant General Nathan F. Twining’s US 20th AAF (the Boeing B-29 Superfortress heavy bomber force in the Mariana islands group) would operate, so far as was feasible, to support the impressions created by the various theatre deceptions.

In overall terms, therefore, ‘Broadaxe’ can be seen as the Pacific equivalent of the ‘Bodyguard’ deception to protect ‘Overlord’, all the more so as the basic approach of ‘Broadaxe’ was similar to that of ‘Bodyguard’ in placing emphasis on distracting the attention of the enemy in as many directions as possible, inducing the enemy to keep substantial forces in theatres distant from that in which the invasion was to take place; and persuading the enemy that the invasion would not be made until after the completion of a long preparatory bombing and blockade campaign.

The period between the initial concept and the authorisation of ‘Broadaxe’ had taken seven months, and in this time a number of other schemes had been proposed and abandoned, these including ‘Mike I’, ‘Bluebird’, ‘Husband’, ‘Bambino’, ‘Valentine’, ‘Stultify’ and ‘Cloak’. The result was that ‘Broadaxe’ had only only a two-month existence before Japanese surrendered, although none of those involved had any inkling of this at the time.

Even in this two-month period, ‘Broadaxe’ required a few alterations. Formosa was replaced as an objective by the Shanghai area, for example, and the idea of accelerated supplies to China was dropped. Another two points were revised late in June. Firstly, MacArthur’s notional landing in Indo-China landing was not, as ‘Broadaxe’ initially ordained, be targeted on the northern part of that country and co-ordinated with an overland attack from China, but redrafted to suggest as an assault at the southern tip, to the south of Saigon, and scheduled for a time early in November simultaneously with the ‘Sceptical’ attack on Bangkok, with the objective of securing the approaches to the Gulf of Siam and establishing fighter cover and convoy protection supporting the Bangkok operation. A genuine blocking action, directed toward northern Indo-China from China in support of Wedemeyer’s offensive, was already planned, and this could be portrayed as intended to support MacArthur’s move in the south by containing Japanese forces in the northern area of Hanoi.

Secondly, the ‘Broadaxe’ element which envisaged a notional accelerated supply rate to China and intensification of activities in the interior of China should probably be eliminated as the Japanese already knew, and were known to know, that supply limitations would preclude any operations over and above ‘Carbonado’. As an alternative, it was suggested that a ‘story’ be created on the basis of the basing in India of two fictitious US parachute regiments for use in the China theatre as they would not be dependent on supply over the ‘hump’ until actually employed.