Despite its ignominious end, the invasion of India had a certain logic to it from the Japanese perspective. The Japanese had a number of forces within SE Asia and within Burma. The Imphal campaign was the culmination of two separate, but mutually reinforcing, strategic imperatives in IJA thought.

There was a pragmatic aspect behind the Indian invasion. Wingate's Chindit penetration into northern Burma had underscored the growing Allied strength in India and had shaken Japanese planning in SE Asia from complacency. There had been some thought given to invading India since 1942, but such plans were now moribund. The Chindits had shown the Japanese the danger Allied forces held for the whole Japanese position in Burma. The IGHQ Directive No. 1776 of January 1944 framed the invasion of India as a prophylactic against further invasions from this sector into Burma.

As counter-intuitive as it might sound, the Imphal invasion fit within the wider defensive reorientation of Japanese grand strategy around 1943. Once it became clear that the tide of the Pacific War had turned against Japan, the IJA began to conceive of a more defensive inner imperial core as the lynchpin of Japanese defenses. Using the remaining IJA forces in both China and SE Asia for brief offensives would eliminate emerging threats on the edges of the inner core and allow Japan to remove these troops to the Pacific once these operations had been completed.

Yet, simultaneous to this pragmatic and defensive thinking was a more ambitious offensive line of thought centered around the IJA 15th Army's chief Lieutenant General Mutaguchi Renya. This general did not see the Chindits so much as a warning of growing Allied strength, but rather as an example that could be emulated. Mutaguchi felt that IJA troops could penetrate the northern Burmese jungles on a modicum of logistical support. Mutaguchi felt that the lack of Japanese air cover would be a benefit as it meant that the Japanese would have to advance along the trails least expected by the Allies. Moreover, Mutaguchi also expected that the Indian National Army (INA) under Chandra Bose would spearhead a wider Indian uprising once the Japanese had penetrated India. Mutaguchi's thoughts dovetailed with the pragmatists in IGHQ, but the differences between the two strategies became apparent once Japanese had reached Imphal. As one IJA officer recalled postwar:

Wingate's Chindit expedition changed Japanese thinking. We thought that north Burma jungles were a defense against British advances into Burma. We now realized that they could be traversed by both sides. We had no intention of advancing into India, just to occupy Imphal and Kohima to further the defense of Burma. But Chandra Bose and Mutaguchi wanted to invade India after occupying Imphal. There was a serious anti-British movement in India, so it was hoped that the INA would operate in Bengal to assist the uprising.

The infighting within the 15th Army became quite intense during the arduous advance in northern Burma and peaked during the battles of Imphal and Kohima. The operation's shortcomings and failures were apparent even before the Imphal battle, but Mutaguchi could not admit that his conception and execution of the operation were deeply flawed.

The problem with both the pragmatists and the dreamers of the IJA was that both were operating on incorrect assessments both of their own capabilities as well as that of the Allies. One of the crucial aspects of Wingate's limited successes was something the Japanese completely lacked: airpower. The lack of air cover had already complicated the operation, but it also proved fatal once the IJA had reached India. Additionally, IJA planning for the operation considered that their tactics and light equipment would be suitable for the job. While this might have been true for the ill-equipped British forces in Malaya and Burma in 1942, the Allied forced in India were considerably stronger. The lack of heavy artillery and armor in any quantity rendered Japanese attempts to take Allied strongpoints futile. Japanese light infantry tactics just did not work very well against an enemy in a prepared position with access to tanks, heavy artillery, and airpower. IJA planners took it as a given that the invasion would be much like that of 1941/42, and in this respect they were sadly mistaken. By the same token, the IJA grossly overestimated the political strength of Bose and the INA. While there was a strong Indian independence movement at the time, this movement was really independent of the Japanese despite British fears to the contrary. Indian Independence was not reliant upon Japanese successes and this meant that it was the INA that needed Japan to remain a relevant player in Indian politics. Mutaguchi's expectation that Bose could launch a wide-scale insurrection once they had reached India was thus putting the cart before the horse. The 15th Army expected to shore up its tenuous position within India through such an insurgency, when it was the other way around. The INA could not operate independently from the Japanese and thus they were hostage to Japanese military fortunes.

In hindsight, the U-Go operation was a foolhardy idea executed rather poorly. While British penetrations had shaken the Japanese out of complacency, it encouraged some of the worst strategic habits within the IJA. Even the pragmatic wing of IJA planning operated on assumptions of Japanese and Allied capabilities that were optimistic to the point of strategic myopia. There were no real good options for Japanese strategic interests in SE Asia at the start if 1944. Allied material superiority meant they were likely to invade Burma sooner or later and Allied airpower was becoming an inescapable reality throughout SE Asia. Unfortunately for Japan, the IJA decided upon the worst of these unpleasant alternatives by launching an invasion it could not win to meet a political objective that could not be met.

Sources

Bond, Brian. British and Japanese Military Leadership in the Far Eastern War 1941-45. Hoboken: Taylor and Francis, 2012.

Drea, Edward J. In the Service of the Emperor: Essays on the Imperial Japanese Army. Lincoln: University of Nebraska Press, 2003.

Katoch, Hemant Singh. The Battlefields of Imphal: The Second World War and North East India. London: Routledge, Taylor & Francis Group, 2016.