Battles and operations involving the Indian National Army (INA) during the Second World War took place in the South-East Asian theatre in the South-East Asian theatre. The INA’s involvement spanned espionage activities during the Malayan campaign in 1942, participation in the Japanese Ha-Go and U-Go offensives in the Upper Burma and Manipur, and later defensive engagements during the Allied Burma campaign.
The INA’s counterpart in Europe, the Indische Legion, saw limited deployment. Although it participated in duties along the Atlantic Wall and was involved in special operations in Persia and Afghanistan, as well as a small deployment in Italy, its overall military role remained minor.
While the INA was not considered a significant conventional military threat, it though not a significant conventional military threat, the INA posed a substantial strategic concern—particularly for the British Indian Army. As Wavell noted, it was considered a target of prime importance.
Background The Indian National Army was initially formed under Mohan Singh consisting of prisoners taken by Japan in her Malayan campaign and at Singapore. Later, after it was reorganized under Subhas Chandra Bose, it drew a large number of civilian volunteers from Malaya and Burma. Ultimately, a force of under 40,000 was formed, although only two divisions ever participated in the battle. In 1943, intelligence and special services groups from the INA were instrumental in destabilizing the British Indian Army in the early stages of the Arakan offensive. It was during this time that the British Military Intelligence began propaganda work to shield the true numbers who joined the INA, and also described stories of Japanese brutalities that indicated, falsely, INA involvement. Further, the Indian press was prohibited from publishing any accounts whatsoever of the INA.
First INA
The prestige of The Raj had suffered a blow with the fall of Malaya and, later, the massive surrender in Singapore. In February 1942, the Indian prisoners of war from the British Indian Army captured there came under the influence of Indian nationalists, notably Mohan Singh Deb, and a large number volunteered to form the Indian National Army with support from Japan and had the stated aim of overthrowing The Raj from India. The formation of this army however, the British intelligence was unaware of until around July 1942, and even then, was unclear on the scale, purpose and organization of the INA.
Espionage in India Intelligence summaries initially did not believe the INA to be a substantial force or have any purpose more than propaganda and espionage purposes. However, by the end of 1942, they had become aware of trained Indian espionage agents (of the INA's Special services group) who had infiltrated into India for the purpose of collecting intelligence, subversion of the army and the subversion of civilian loyalty. This information was derived to a large extent from some of the agents themselves who gave themselves up to the authorities after reaching India. However, the intelligence was also aware at this point of misinformation being spread about the INA itself by the agents who concealed their purpose and professed to pass on intelligence from local knowledge. More troubling for the military command were the activities of the INA agents in the battle fields of India's eastern frontier in Burma.
Espionage in Burma frontier Around this time, the Quit India movement had reached a crescendo within India, while the continuing British reversals at Burma further affected the morale of the army. The Irwin's First Campaign had been contained and then beaten back by inferior Japanese forces at Donbaik. Intelligence analysis of the failure, as well as Irwin's own personal analysis of the campaign attributed significant demoralization and rising discontent amongst Indian troops due to the subversive activity of INA agents at the frontline, as well as rising nationalist (or “Pro-Congress”) sentiments. The activities of these agents were addressed at the Sepoys, and these found enough support to successfully encourage defection without attracting the attention of the officers commanding the units. Soon, defection by British Indian troops had become a problem significant and regular enough in the Burma theatre to form a regular part of the intelligence summaries in the first half of 1943.
Second INA
The strategy of operation of the Indian National Army, in relation to the opening Japanese offensive, was to be of a guerrilla force that would initiate defections among the British Indian troops, as well as garner support and sympathy among the local population for the INA.
The INA's own strategy was to avoid set-piece battles for which it lacked arms, armament as well as manpower. Initially, it sought to obtain arms as well as increase its ranks from Indian soldiers expected to defect. Once across the hills of North-East India and into the Gangetic plain, it was expected to live off the land and garner support, supplies, and ranks from amongst the local populace to ultimately touch off a revolution. Prem Kumar Sahgal, an officer of the INA, once Military secretary to Subhas Chandra Bose and later tried in the first Red Fort trials, explained that although the war itself hung in balance and nobody was sure if the Japanese would win, initiating a popular revolution with grass-root support within India would ensure that even if Japan lost the war ultimately, Britain would not be in a position to re-assert its colonial authority, which was ultimately the aim of the INA and Azad Hind.
The plans for operation decided between Bose and Masakazu Kawabe specified that the Japanese and INA forces were to follow a common strategy. The INA was to be assigned an independent sector of its own, and no INA unit was to operate at less than battalion strength. For operational purposes, the Subhas Brigade was assigned under the command of the Japanese general headquarters in Burma. The general operations plan envisaged the INA units pushing to Kohima and Imphal with Japanese forces, and as the latter fell, the INA was to cross the Brahmaputra and enter Bengal, beginning the next phase initialing local resistance and revolts within India.
Arakan
In March 1944, the Japanese forces began its offensive into India's eastern frontier. The plans for the offensive directed three divisions from Kawabe's Burma Area Army to initiate a diversionary attack at Arakan and cover the southern coast while another two divisions watched Stillwell and Chiang Kai-shek's forces in the north. In the center, three divisions from Mutaguchi's 15th army were pushed into Manipur to capture Imphal, scattering British forces and forestalling any offensive movements against Burma. The INA's Special Services Group, redesignated as the Bahadur Group worked with the advanced Japanese units and pathfinders in the opening stages of the Japanese offensive in the upper Burma region and into Manipur. These were tasked to infiltrate through British lines and approach units identified as consisting of significant Indian troops and encourage them to defect. Fay quotes British Intelligence sources to confirm that these units achieved some success in these early stages. In early April a unit of the Bahadur Group, led by Col. Shaukat Malik, broke through the British defenses on 14 April 1944 to capture Moirang in Manipur. The Azad Hind administration took control of this independent Indian territory.
Meanwhile, the 1st battalion of the INA's 1st Guerrilla regiment, lightly armed, was directed towards the south to participate in the diversionary attack. The unit left Rangoon in early February to reach Prome. From Prome, the unit marched across the Chin Hills to reach the Taungup and then up the coast to reach Akyab in early March. By this time the Arakan offensive was nearing its end, and although it had been a successful diversion, Kawabe's forces had failed to capture and destroy Messervy's 17th Indian Division. The 1st battalion marched up the Kaladan river and by middle of March approached Kyauktaw, east of Mayu peninsula. Subsequently, the unit progressed slowly but successfully against Commonwealth African units before crossing the Burma-India border north of Akyab, occupying Mowdok near Chittagong.
Imphal and Kohima
The Arakan offensive was intended to create a diversion for Mutaguchi's forces, while drawing out and destroying as much of the British reserves as possible. In the center, Mutaguchi's 15th Army was to be the decisive factor in the Manipur Basin. As the battle progressed, Mutaguchi's 31st Division engaged the commonwealth forces at Kohima, while the 15th Division was detailed to move down Kohima road to the North-west of Imphal. The main force detailed to engage Imphal, the 33rd Division (the Yamamoto Force, led by Yamamoto Tsunoru), however, was to approach from the south-east via the Tamu Road that had been built by the Commonwealth forces earlier. The INA's four guerrilla regiments (except for No.1 Battalion) were directed to Tamu road and detailed to push into India as Imphal falls.
The 2nd and 3rd battalions, led by Shah Nawaz Khan, crossed the Chindwin at Kalewa and, after marching up the valley of the Myittha, reached the edge of Chin Hills below Tiddim and Fort White at the end of March. From this position, a unit of the 2nd battalion moved to relieve Japanese forces at Falam while a second company moved to Hakha. The 3rd battalion was meanwhile moved to Fort White-Tonzang area in anticipation of fall of Messervy's forces that would allow it to receive possible volunteers, as well as begin its advance into India.
Among the responsibilities of Khan's forces was the protection of the southern flank of Mutaguchi's forces from Chin irregulars. From the bases at Falam and Hakha, Khan's forces sent out forward patrols and laid ambushes, with some successes, for the Chin guerrillas under the command of a British officer, taking a number of prisoners. In the middle of May, a force under Khan's Adjutant, Mahboob Ahmed, attacked and captured the hilltop fortress of Klang Klang.
With the Messervy's 17th Indians breaking out, however, the 3rd battalion could not be employed in its original perceived role. It was at this time the unit, for whatever reasons, was employed at repairing roads that is widely reported when discussing the INA's role in the Japanese offensive. Learning of this development, an enraged Shah Nawaz ordered it back to base.
With the offensive more or less stopped by mid-May in the face of fierce resistance from the commonwealth forces, Khan's forces were redirected to engage Kohima. Khan moved across the Japanese rear with the 3rd Battalion and portion of the 2nd. By the time he reached Ukhrul however, Mutaguchi's 31st division had begun withdrawing from Kohima. Khan decided to attack Imphal instead.
The 2nd Guerrilla Regiment, or the Gandhi Regiment as it was called, consisted of two battalions. Led by Inayat Kiyani, it was directed along the axis of the 15th Army's offensive. Like the 1st Guerrilla, it had crossed the Chindwin at Kalewa. From Kalewa, the 2nd Guerrilla turned north to reach the vicinity of Tamu in late April. The INA high command was informed at this time of the Yamamoto force's impending assault on the airfield at Palel. The INA unit was still far away. Kiyani picked a force of three hundred under Maj. Pritam Singh that could advance faster. Armed lightly and without machine guns, the unit was directed to attack the airfield from the south while Japanese forces engaged the eastern defenses.