The Battles of Imphal and Kohima, 1944

In December 1941, the Empire of Japan declared war on the United States and Great Britain. Within a few short weeks, Japan’s military invaded Malaya, Thailand, the Dutch East Indies, Shanghai, the Philippines, and Hong Kong. This created a sphere of influence stretching from Mongolia to Manilla. In January 1942, Japan invaded British-held Burma and seized the capital Rangoon in March that same year. Demoralised and exhausted, British and Commonwealth forces fell back beyond the Chindwin River in Burma and prepared for an eventual counterattack.

With the Allies’ retreat to India, British High Command was faced with a difficult problem. Their forces were exhausted and demoralised and facing a capable and aggressive enemy. After two years of reinforcement and retraining, Commonwealth forces in India were reorganised into the 14th Army in November 1943. Under the command of General William Slim, the 14th was to be the spearhead for an eventual invasion of Burma. 

By August 1943 however, the Japanese were aware of British preparations. Allied units such as the Chindits for example, led by Major-General Orde Wingate, had been operating behind enemy lines in Northern Burma since February 1943. Lieutenant General Renya Mutaguchi created a plan to disrupt Allied preparations by invading India first, codenamed Operation U-Go. The attack would target the staging towns of Imphal and Kohima, before moving onto major Indian cities such as Dimapur and Delhi. Mutaguchi believed that a Japanese ‘March on Delhi’ would not only throw the Allies into disarray but would spark a nationwide revolt against British rule in India.

The 77th Indian Infantry Brigade, or Chindits as they became known, was the brainchild of Major-General Orde Wingate. Wingate was an eccentric officer, remembered fondly by his men for casually eating raw onions and giving orders while naked. Wingate had developed a grasp of guerrilla warfare following time in Palestine and Abyssinia (present day Ethiopia), and on transferring to India in March 1942, began applying those same principles to the Burma Campaign. The Chindits role was to insert themselves deep behind enemy lines and use the jungle terrain to disrupt Japanese supply and communications. This became known as “long range penetration” – a tactic frequently used by the SAS in North Africa. Commonwealth forces were unused to jungle conditions, and casualties were high. Humid temperatures of above 40 degrees Celsius, diseases such as Beri Beri, and sporadic air drops of supplies made for grim experiences for the soldiers.

The first Chindit operation, codenamed Longcloth, took place in February 1943. 3,000 men divided into columns marched over 1,000 miles into the Burmese jungle. The operation caused little material damage to the Japanese, but it did change their attitude towards India. Longcloth had shown them that the Allies could strike deep behind Japanese lines, and an invasion of India would solve the problem. A second, larger, operation, codenamed Thursday, was launched in March 1944. 20,000 men were inserted behind advance Japanese forces by air and began disrupting supply routes critical to Operation U-Go. 

Unfortunately, Orde Wingate was killed in a plane crash on 24th March 1944. With Wingate gone, the Chindits came under the command of the American General Joseph Stilwell. Stilwell was known for his anti-British attitude and did not appreciate the strengths of the Chindits. He kept them in the jungle during monsoon season and used them to assault enemy strong points. When the brigade was eventually withdrawn after 4 months and 24 days, every single soldier was admitted to hospital. Many were suffering from a range of illnesses including malaria, dysentery, and malnourishment. 

By January 1944, the Allies noticed the build-up of Japanese troops along the Chindwin River. Instead of facing them in the dense jungle, Allied high command chose to withdraw their forces to the Imphal Plain, stretching the Japanese lines of supply and communication. Unfortunately, not all divisions could pull back in time. A rapid diversionary attack by the Japanese on 4th February completely encircled the 7th Indian Division in the Arakan region of Burma. With their headquarters overrun, the trapped soldiers regrouped at the ‘Administrative Box’; a supply depot and field hospital for the region around Ngakyedouk Pass.

The besieged remnants of the 7th Indian Division held off repeated Japanese attacks without resupply for a week. On the 11th February, the RAF established air superiority and delivered the first of 1,600 tons of supplies to the defenders of the Admin Box. This effort allowed the 7th Indian Division to hold the Ngakyedouk Pass until relieved by the 5th Indian Division, forcing the Japanese to retreat for the first time in the war. The bitter fight cost approximately 2,000 Allied casualties while the Imperial Japanese Army lost approximately 5,000 men. General William Slim described it as “the turning point in the Burma Campaign”.

The Japanese 15th Army began Operation U-Go by crossing the Chindwin River in Burma on 6th March 1944. Two divisions, the 15th Infantry and 33rd Infantry, advanced on Imphal. As planned, the Allies began a steady withdrawal back to the Imphal plain. Some units would remain in the field to slow the Japanese advance. The 50th Indian Brigade, for example, made a stand at a village called Sangshak, hoping to delay the Japanese long enough for reserves to reinforce Imphal. For four days, from 22nd March, the Japanese launched multiple attacks at all hours of the day and night to dislodge the defenders. 

On the 23rd, the defenders of Sangshak discovered the body of a Japanese officer. On his person, they found detailed plans for Operation U-Go. This revealed that a third division, the Japanese 31st Infantry, was making for Kohima, a vital supply hub for Imphal. A brigade runner was dispatched to slip through the Japanese siege lines and take the vital information back to Imphal. As with the Admin Box, the besieged Allied defenders of Sangshak could only be resupplied by air, but most of the supplies were dropped over a wide area and taken by the Japanese. On 26th March 1944, the 50th Indian Brigade was finally ordered to retreat. The survivors broke out in the evening and spent three days walking the 30 miles through dense jungle to Imphal. 

Further north, 280 men of the 1st Assam Regiment at Jessami stood in the path of the Japanese 138th Infantry Regiment as they advanced on Kohima. As with Sangshak, the larger Japanese force had surrounded Jessami by 28th March, but the garrison was ordered to fight ‘to the last man, the last round’. Japanese attacks began that very night. The Indian National Army, made up of Indians who wanted to expel the British from India, fought with the Japanese at Jessami. Throughout the battle, INA soldiers called out to the men of the 1st Assam and asked them to turn against their British officers. 

On 30th March, the rest of the Japanese 31st Division reached Jessami, increasing the odds against the small garrison. The Assam mortar batteries were silenced by Japanese artillery and lines of communication with Kohima were cut. Determined Japanese attacks continued to be repulsed by an even more determined defence. Attempts to resupply the besieged village by air fell apart when, as with Sangshak, the supplies drifted towards Japanese lines. Finally, on 31st March, a runner arrived from Kohima with orders to retreat. The delays to the Japanese advance, caused by the stubborn defence of Sangshak and Jessami, bought the British and Indian forces enough time to reinforce and resupply Kohima and Imphal. 

British high command initially believed that Kohima was safe from a direct attack because of the mountainous jungle terrain surrounding the small town. As it turned out, they were wrong. Colonel Hugh Richards arrived in Kohima on 23rd March and began organising a defence on the heights above the town. On 3rd April, as the survivors of Jessami arrived in the town, the first Japanese troops were spotted on the perimeter. Throughout the night of 4th April, Colonel Richards noted the arrival of the rest of the Japanese 31st Division, 15,000 strong. Richards had a garrison of only 1,500. 

When the siege began, the defenders were set up on a series of hills overlooking Kohima from north to south: Hospital Ridge, Garrison Hill, Kuki Piquet, Supply Hill, Detail Hill, and Jail Hill. From the 5th to 18th April, determined Japanese attacks forced British and Indian forces back to a small defensive position on Garrison Hill. At the height of the siege, the Allies held just 350 square metres of blasted hillside, separated from the Japanese only by the width of a tennis court. 

The situation at Kohima was becoming critical. The British and Indian defenders were surrounded and running out of essentials like food, water, ammunition, and medical equipment. The close-quarter fighting made it difficult to supply the garrison by air, and vital supplies would often drift over to the Japanese by mistake. But, by 14th April, help was on the way. The British 2nd Division, moving down from Dimapur to the north, broke through the Japanese roadblock at a village called Zubza which opened the way for a relief column. Nightly Japanese attacks on Kohima Ridge continued, even as lead elements of 2nd Division made their way to relieve the battered defenders on Garrison Hill. The Allies in turn went on the offensive, attempting to retake positions lost weeks before.

The mental and physical toll on the Japanese 31st Division had also been high. Lieutenant General Kotoku Sato, commander of the 31st, saw that his men were starving, lacking in vital supplies, and wracked with diseases such as malaria and Beri Beri. On 31st May 1944, Sato disobeyed instructions from Lieutenant General Mutaguchi and gave the order to retreat. After eight weeks of bitter fighting, pressure on the garrison at Kohima finally began to ease. As the Japanese retreated, the Allies began offensives to open the Imphal Road and help British and Indian troops to the south, which they achieved on 22nd June. The Battle of Kohima had cost the Japanese about 7,000 men. The Allies had suffered 4,000 injured or dead.

Before Operation U-Go, Imphal had been a growing administrative  centre for Allied operations in Northern India. It was also the base for Allied 4th Corps in their planned invasion of Burma. This made the town a high value target. As the Japanese 31st Division marched on Kohima, the 15th and 33rd Divisions began to surround Imphal. By 15th April, the last road out of Imphal was cut by the Japanese, placing the town under siege.

As with Kohima, Sangshak, and the Admin Box, Imphal now had to be supplied by air. Allied air power allowed for not just the resupply of food, medicine, and ammunition, but also reinforcements. Between 18th and 27th March, two brigades from the Indian 5th Division were flown in from Arakan in Burma to support the defenders of Imphal. Control of the airfields became a priority for both the Allies and the Japanese. The Japanese took control of the Nunshigum Heights overlooking Imphal Main airport on the 7th April. This required the newly transported Indian 5th Division to take back the heights on the 13th April.

Another area that saw bitter fighting was the village of Palel, south of Imphal, which hosted one of only two all-weather airfields in Allied hands. Control of the ‘Shenam Saddle’, a ridge of hills overlooking the airfield, was crucial for both sides. Attacks on Palel and Nunshigum continued into May, with positions changing hands several times. This fierce fighting however came at a cost. The Japanese offensive had relied on speed and surprise to achieve their objectives. By mid-May, mounting casualties and decreasing supplies were beginning to take their toll on Mutaguchi’s 15th Army. 

With the Japanese retreat at Kohima, fresh British and Indian troops were also now pushing from the north. By 22nd June, supplies and heavy armour could also begin reinforcing the defenders via the newly opened Kohima to Imphal road. Mutaguchi demanded fresh attacks, but his army was a remnant of its former self, suffering from hunger, disease, and daily casualties. Worse still, monsoon season had begun, making resupply by land or air difficult. Operation U-Go was a failure.

By the end of the battle, the Allied air force had delivered 19,000 tons of supplies to Imphal, thanks to the efforts of British and Indian units to keep the airfields in Allied hands. 

With the Japanese now on the defensive at Kohima and Imphal, Lieutenant General Renya Mutaguchi called off Operation U-Go on 3rd July 1944. Over the course of four months, the Japanese 15th Army had suffered 53,000 casualties. The Allies lost approximately 16,500 soldiers in the defence of India. The remaining units of the 15th Army were ordered back across the Chindwin River in Burma, but as monsoon season began, the exhausted Japanese troops found themselves with little food, shelter, ammunition, or medical supplies. 

As the Japanese retreated across the Chindwin River, the Allies rallied and began their own plans of invasion. Operation Capital, the invasion of Burma, began in January 1945. After years of fighting in jungle terrain, British, Indian, Gurkha, and African forces broke onto the open plain of central Burma. The Japanese under General Heitaro Kimura, Commander-in-Chief of the Burma Area Army, attempted to cut Allied supply routes, but lacked air support. As a result, the Allies could be resupplied and reinforced by the air up until the beginning of the monsoon season. The city of Mandalay was captured on 20th March 1945, followed by the capital of Burma, Rangoon, on 3rd May 1945. A week after the fall of Rangoon, Germany formally surrendered to the Allies.

Yet as fighting ended in Europe, the Japanese continued to offer stiff resistance. Throughout June and July, in Burma, the Philippines, Sarawak, and Okinawa, Allied troops fought to dislodge entrenched Japanese positions. In Burma, for example, the Japanese 28th Army withdrew to the Pegu Yomas uplands where they were surrounded by the advancing Commonwealth forces. In their attempt to break free of this encirclement, the Japanese lost over 12,000 men. 

In 2013, the National Army Museum hosted a poll in which the Battle of Imphal was voted ‘Britain’s Greatest Battle’. If Imphal had fallen, Britain’s involvement in the war in the east would have been put in jeopardy. Airfields north of Imphal at Dimapur would also have been put at risk. These airfields were essential for the supply of the Chinese National Army still fighting the Japanese in Yunnan province. The fall of both these fronts would have freed more Japanese troops for offensives against American and Australian forces in the Pacific. The actions of ‘The Forgotten Army’ helped prevent this from happening. 

Following the Second World War, both India and Burma would campaign for independence from Britain, showing their contribution to the war effort on both the Allied and Japanese sides. The battles of Imphal and Kohima were not only critical to victory in Asia, but also key factors in the creation of an independent India.