Battle of Imphal-Kohima
Contributor: C. Peter Chen
By summer of 1943, the British forces were beginning to dominate in the skies with Royal Air Force (RAF) aircraft operating out of India. While Japan had no original plans to invade India, Lieutenant General Renya Mutaguchi of the Japanese 15th Army knew that an offensive into India was the only way he could eliminate the aerial threat. Controlling northeastern India would also create a larger buffer zone between India and Burma. Imphal was the state capital of Manipur in northeastern India and was situated amidst a plain where an invading army from the east must march across. Additionally, a Japanese-controlled northeastern India would also cut off "the Hump" as an aerial supply route into China. As such, it was no surprise that British plans to invade Burma used Imphal as a launch point for ground troops, the same place Mutaguchi also targeted. Mutaguchi's excursion into India was originally rejected by his immediate superiors, but what would eventually become Operation U (U-Go) was approved by Southern Expeditionary Army and the Imperial General Headquarters (IGHQ) in Tokyo, Japan.
Mutaguchi planned to pin-down or destroy the forward-deployed Indian troops with Lieutenant General Motoso Yanagida's 33rd Division, then the 33rd Division will be reinforced by Lieutenant General Masafumi Yamauchi's 15th Division to take Imphal. At the same time, Lieutenant General Kotoku Sato's 31st Division was to attack Kohima, a village on a major road into Imphal, an administrative center of the state of Nagaland, and near the important airfield at Dimapur. Mutaguchi did not receive support from his field generals for his plans; most of them believe the attack plan was too risky.
The city of Imphal was defended by the Indian IV Corps under the command of Lieutenant General Geoffrey Scoones, who reported to Lieutenant General William Slim. As the Japanese troops attacked, Slim and Scoones attempted to move this troops from their forward positions back into the plains near Imphal, forcing the Japanese to fight with a longer supply line, but Scoones had reacted too late; while the Japanese offensive began by crossing the Chindwin River on 8 Mar, Scoones did not give the order to fall back near Imphal until 13 Mar. As a result, the Indian 17th Division allowed its supply dumps to become captured by the Japanese and become encircled. However, the 214th Regiment of the 17th Division successfully counterattacked at Tuitum Saddle on 18 Mar, allowing the division to recover part of the captured supplies and safely retreated to Imphal on 4 Apr 1944.
The Japanese followed the withdrawing Indian troops closely. As soon as the Indian 17th Division reached Imphal, the attack began. The Japanese 33rd Division attacked from Bishenpur from the south, though that attack was cautious and slow. From Tamu, Major General Tsunoru Yamamoto, commanding units from both the 15th and 33rd Divisions and two brigades of Indian troops attacked Shenam Saddle near Imphal, and was quickly halted by the Indian troops at this easily-defended junction. From the north, the remainder of the 15th Division attacked and first captured a small supply dump at Kangpokpi then captured Nungshigum Hill which overlooked Imphal's main airfield. The initial attack did not go as well as Mutaguchi originally planned, and the possibly prolonged campaign was now threatened by a long supply line through the Burmese jungles. It was exactly what his field generals warned of. To make matters worse particularly for the Japanese 31st Division, the British 23 LRP Brigade had been seriously disrupting Japanese supply operations behind the lines, making even foraging to the east of Kohima nearly impossible.
The attack on Kohima began around the same time, which was weakly defended by the Assam Regiment and some of the paramilitary Assam Rifles. The Indian 161st Brigade was originally posted at Kohima, but it was moved out of Kohima to Dimapur shortly before the attack. On 3 Apr, the 31st Division attacked Kohima Ridge which overlooked the main supply route between Imphal and Kohima. The siege of Kohima began on 6 Apr. Japanese mortar fire rained down on the Indian troops who were poorly supplied and lacking drinking water. Nevertheless, the Indian troops held, and combat turned into a stalemate.
On 13 Apr, the Indian 5th Division counterattacked at Nungshigum Hill outside of Imphal with support from artillery and M3 Lee tanks. The Japanese had neither anti-tank weapons nor artillery; these heavier guns had been decided against as Mutaguchi planned for a swift campaign, and these guns were simply too bulky to carry through the dense jungle. As a result, the hill was taken back by the Indian troops after dealing heavy casualties on the Japanese.
On 15 Apr, the British 2nd Division which had been in training in southern India arrived at Dimapur near Kohima. The fresh troops relieved the Indian 161st Brigade, who rested for three days before going on a counterattack toward Kohima. As the siege at Kohima listed on about 20 Apr, the incoming troops were shocked by what they witnessed. The once picturesque village was now in ruins, building walls marked with bullet holes and surrounding hills covered by broken trees. "Every inch of ground were disputed in the bloodiest and most desperate hand-to-hand fighting", described historian Frank McLynn.
By 1 May 1944, the Indian troops had a firm hold on the line, and their British commander could entertain the notion of a counter offensive, especially with the arrival of the 33rd Brigade of the Indian 7th Division on 4 May. Although the Japanese line was tough to break, the supply situation had become critical. The Japanese divisions had not been receiving adequate supplies, including food, and the soldiers' health were becoming dangerously poor due to malnutrition. The situation took a worse turn on 12 May when the Indian 114th Brigade arrived near Kohima. Under Montagu Stopford's command as XXXIII Corps, British and Indian forces attacked southward from Kohima toward Imphal. The Japanese troops, despite the difficult conditions they were in, fought back fiercely. Nevertheless, the Japanese troops were drove out of the Kohima region by the end of May; with 38 3.7-inch mountain howitzers, 48 25-pound field guns, and 2 5.5-inch medium guns, the Japanese could hardly hold their line for an extended amount of time. The RAF also stepped up their involvement, bombing and strafing Japanese positions, destroying Japanese morale that had already been faltering.
On 25 May, troops near Kohima reported that unless adequate food supplies had been delivered, the troops there could not last past 1 Jun; in fact, General Sato threatened he would disobey direct orders and withdraw if he did not see supplies flowing in. On 31 May, Japanese troops withdrew from Naga village and fell back southward.
The XXXIII Corps was then joined by IV Corps and attacked the Japanese troops further along the Dimapur-Imphal road on 22 Jun near Milestone 109. When the battle at Milestone 109 was won by the British and Indian troops, the siege of Imphal was lifted.
The Japanese 33rd Division, now under command of Lieutenant General Nobuo Tanaka and freshly reinforced by battalions from 53rd and 54th Divisions, continue to assert pressure on the Indian troops despite the recent setbacks. The 33rd Division nearly broke through the line set by the Indian 17th Division at Bishenpur, but in the end the Japanese suffered such a high casualty that the offensive was called off by the front line generals on 3 Jul 1944. In fact, by this time, many Japanese units were unfit for combat due to various reasons that they had already been disobeying orders to press forward. Reluctantly, Mutaguchi withdrew the remnants of the Japanese 33rd Division from Imphal, India back into Burma. The Japanese defeat at Imphal and Kohima represented the largest defeat in Japanese military history. Of the 65,000 front-line troops, 30,000 were killed, 23,000 were wounded, and 600 were captured; among the 50,000 support troops, there were 15,000 casualties. The Allies only suffered 17,500 casualties in comparison.
The Allied victory at Imphal and Kohima allowed the RAF to continue assert pressure from the skies on Japanese troops in Burma. "The Hump" into China was also allowed to continue because of the successful defense. The RAF also contributed greatly to the battle directly as RAF aircraft delivered most of the supplies the British and Indian forces needed; the RAF flew 19,000 tons of supplies and 12,000 men into the Kohima-Imphal region and flew out 13,000 casualties and 43,000 non-combatants.
Louis Mountbatten latter described the Allied victory at Imphal and Kohima as "probably one of the greatest battles in history,... in effect the Battle of Burma.... [It was] the British-Indian Thermopylae."
Frank McLynn, The Burma Campaign
Battle of Imphal-Kohima Interactive Map
Battle of Imphal-Kohima Timeline
|9 Jan 1944||Prime Minister Hideki Tojo authorized the plans for Operation U-Go against northeastern India.|
|5 Mar 1944||William Slim requested his superiors to assign an additional division to defend Kohima and Dimapur, India. He would only receive two battalions of Indian parachute troops.|
|7 Mar 1944||A regiment from the Japanese 33rd Division crossed the Manipur River in Burma toward the Burmese-Indian border toward Tiddim, Burma.|
|8 Mar 1944||Japanese troops launched a major offensive across the Chindwin River in Burma toward Imphal, India. Meanwhile, another regiment from the Japanese 33rd Division crossed the Manipur River in Burma toward the Burmese-Indian border toward Tiddim, Burma.|
|13 Mar 1944||Lieutenant General Geoffrey Scoones realized the Japanese attack on Tiddim, Burma was a part of a major offensive, and retracted his previous order, allowing troops at Tiddim to fall back.|
|14 Mar 1944||William Slim requested Louis Mountbatten to divert aircraft originally assigned to fly the Hump to instead bring men and supplies to Imphal, India. Mountbatten agreed, diverting 30 transport planes to bring the Indian 5th Division to Imphal and Dimapur, India.|
|15 Mar 1944||After dark, the Japanese 15th Division crossed the Chindwin River in Burma toward India as part of the second wave of the Japanese offensive.|
|17 Mar 1944||Japanese and Anglo-Indian troops clashed at Tonzang, Burma.|
|18 Mar 1944||Japanese 15th Division reached Ukhrul, India, which was about 50 miles from Imphal, India. Behind them, Japanese 31st Division crossed the Chindwin River in eight columns toward India.|
|20 Mar 1944||Japanese troops captured Ukhrul, India, defeating the Indian Parachute Regiment and a brigade from the British 23rd Division.|
|22 Mar 1944||Japanese troops crossed the Burmes-Indian border into the Indian state of Manipur and attacked Sangshak from the north.|
|23 Mar 1944||Japanese troops assaulted an Allied defensive position in the crater of an extinct volcano near Sangshak, India, initially failing to take the position. Shortly after, Allied aircraft dropped supplies to the Indian troops at Sangshak, India, but most of the supplies fell behind Japanese lines. As Indian 152nd Parachute Battalion attacked from the volcano crater to regain the supplies, the Japanese drove them back, causing heavy casualties.|
|24 Mar 1944||The 3rd Battalion of the Japanese 58th Regiment arrived in the Sangshak, India region as reinforcements.|
|25 Mar 1944||The 3rd Battalion of the Japanese 60th Regiment attacked Allied positions at Sangshak, India. Meanwhile, Louis Mountbatten requested the Anglo-American Combined Chiefs of Staff for more aircraft to supply Imphal, India, which would be denied.|
|26 Mar 1944||Troops of Japanese 60th Regiment attacked Sangshak, India after dark, but got lost in the darkness, and many men were trapped in the open in the next morning.|
|27 Mar 1944||Japanese 58th Regiment launched an all-out attack on Sangshak, India. Brigadier Maxwell Hope-Thompson, commanding officer of the defending Allied troops, ordered a retreat from Sangshak at 1800 hours. On the same day, William Slim requested the British 2nd Division to help defend nearby Dimapur.|
|29 Mar 1944||Japanese troops cut the road between Imphal and Kohima, India. Meanwhile, the Anglo-American Combined Chiefs of Staff retracted a decision made earlier and diverted additional transport aircraft from the Mediterranean Sea theater of war to the Burma-India theater of war. Louis Mountbatten had requested them to help the defense of the Imphal region in India; incidentally, the initial aircraft embarked on transporting the Indian 5th Division to Imphal and Dimapur completed the task on this date after 758 sorties.|
|30 Mar 1944||Japanese troops besieged Imphal, India.|
|1 Apr 1944||Japanese troops captured Nippon Hill near Imphal, India.|
|3 Apr 1944||General Montagu Stopford ordered Major General R. P. L. Ranking to move the Indian 161st Brigade from Kohima to Dimapur in India. Ranking believed this was a bad move as Kohima would be a Japanese target, and appealed to William Slim; Slim sided with Stopford.|
|4 Apr 1944||On the Imphal front in India the Japanese 51st Regiment of 15th Division commenced attacks on 123rd Indian Brigade's positions, while the Japanese 31st Division attacked the village of Kohima.|
|5 Apr 1944||On the Imphal front in India, the Japanese 60th Regiment probed south towards a large store dump, where staff of the British 221st Advanced Ordnance depot, under continuous and heavy fire, repeatedly foiled the Japanese infiltration attacks for three days. Meanwhile, realizing that the movement of Indian 161st Brigade from Kohima to Dimapur was a poorly calculated move, he moved the brigade back; with no room in Kohima for the troops of the brigade, they settled down at Jotsoma 2.5 miles to the northwest to support from a distance.|
|6 Apr 1944||After dark, Japanese troops launched an attack at Kohima, India, reaching the buildings at the edge of the village before the attack was halted early in the next day.|
|8 Apr 1944||Japanese troops moved into the ground between Kohima and Jotsoma in India, cutting off the Indian 161st Brigade from being able to assist in the defense Kohima.|
|9 Apr 1944||Japanese troops captured Kanglatongbi and began to surround the Anglo-Indian troops at Imphal, India. To the north at Kohima, India, Japanese troops captured GPT ridge, forcing the British troops to fall back to Garrison Hill.|
|11 Apr 1944||Anglo-Indian and Japanese troops began a four-day clash at Bunker Hill near Kohima, India.|
|16 Apr 1944||Indian 5th Brigade arrived at Jotsoma, India, allowing Indian 161st Brigade to prepare for an advance toward Kohima.|
|17 Apr 1944||General Renya Mutaguchi ordered Lieutenant General Kotoku Sato to capture Kohima, India by 29 Apr 1944. On the front, Anglo-Indian and Japanese troops clashed at Garrison Hill and FSD Hill near Kohima.|
|19 Apr 1944||After sundown, the Japanese launched three separate attacks against Anglo-Indian positions near Imphal, India, some supported by medium tanks; none of the attacks achieved their objectives.|
|20 Apr 1944||The Japanese siege of Kohima, India was beginning to be lifted.|
|21 Apr 1944||Japanese troops captured Crete West hill near Imphal, India.|
|22 Apr 1944||Japanese attacks overran some Anglo-Indian defensive positions near Imphal, India, but no major progress was made. Near Kohima to the north, Anglo-Indian troops attacked Garrison Hill after sundown. Behind the Japanese lines, Lieutenant General Renya Mutaguchi visited the front lines and relieved Major General Motozo Yanakida for his perceived lack of aggressiveness, replacing him with Major General Nobuo Tanaka.|
|23 Apr 1944||Anglo-Indian troops attacked Ningthoukhong, India.|
|25 Apr 1944||Anglo-Indian troops attacked Ningthoukhong, India.|
|27 Apr 1944||Anglo-Indian troops attempted to attack the Japanese positions on the far side of the tennis court in Kohima, India.|
|29 Apr 1944||After dark, Japanese troops launched a counterattack at Kohima, India.|
|1 May 1944||Anglo-Indian troops attacked Crete West hill near Imphal, India.|
|3 May 1944||Indian 4th Brigade attacked GPT ridge near Kohima, India, which failed to capture all Japanese positions.|
|6 May 1944||During the day, 25 Japanese Zero fighters attacked Bishenpur, India. After sundown, Japanese troops attacked Tengnoupal, India.|
|7 May 1944||During the day, Anglo-Indian troops attacked Jail Hill near Kohima, India, which was repelled by Japanese troops and suffered heavy losses. To the south, the British offensive from Imphal, India into Burma was called off after lack of success. After sundown, Japanese troops attacked Tengnoupal, India and overran some Allied defensive positions.|
|10 May 1944||Japanese troops attacked Scraggy Hill near Imphal, India. 30 kilometers to the southwest, Bishenpur was attacked by a group of Japanese Zero fighters.|
|12 May 1944||Anglo-Indian troops counterattacked at Tengnoupal, India, regaining territory lost during the Japanese attacks between 6 and 8 May 1944.|
|13 May 1944||By this date, Anglo-Indian troops had control of Jail Hill, GPT ridge, and FSD ridge near Kohima, India.|
|15 May 1944||Anglo-Indian troops pushed Japanese troops out of Potsangbam, 2 miles south of Bishenpur, India. To the north near Kohima, Indian 33rd Brigade captured Treasury Hill with little Japanese opposition.|
|16 May 1944||Major General Nobuo Tanaka ordered a two-pronged offensive toward Bishenpur and the plains near Imphal in India.|
|18 May 1944||Anglo-Indian troops attacked Japanese positions at Ninthoukgong, India.|
|19 May 1944||An Anglo-Indian attack on Naga, India was repulsed with heavy casualties.|
|20 May 1944||Japanese troops evacuated the forward-most positions near Imphal, India. Meanwhile, a bloody clash took place between Japanese and Anglo-Indian troops at Torbung.|
|21 May 1944||Anglo-Indian troops captured Kanglatongbi, India.|
|24 May 1944||Japanese troops captured Gibraltar Hill and attacked Lone Tree Hill near Imphal, India. To the north at Kohima, Indian 7th Division began an offensive against Dyer Hill, Pimple Hill, and Big Tree Hill.|
|29 May 1944||The Anglo-Indian attack on Ninthoukgong, India was halted after capturing the northern half of the town.|
|30 May 1944||Major General Nobuo Tanaka canceled his offensive in the Imphal region in India after incurring heavy losses. To the north at Kohima, the Indian 7th Division assault on Dyer Hill, Pimple Hill, and Big Tree Hill, which began on 24 May, was repulsed with heavy casualties.|
|2 Jun 1944||Major General Nobuo Tanaka ordered a final attack at Imphal, India despite overwhelming odds. Near Kohima to the north, Japanese troops evacuated from the village of Naga.|
|7 Jun 1944||Anglo-Indian and Japanese troops engaged in a bloody clash at Ninthoukgong, India.|
|9 Jun 1944||The Japanese frontal-attack on Gurkha positions on Scraggy Hill was met with heavy losses, particularly to superior British firepower and air support.|
|20 Jun 1944||Japanese troops captured Forest Hill near Imphal, India but failed to capture Plum Hill, another nearby objective.|
|22 Jun 1944||In India, Indian 6th Brigade from Kohima made contact with Indian 9th Brigade from Imphal on the Imphal-Kohima Road that had been held by the Japanese.|
|24 Jun 1944||British Lieutenant General Geoffrey Scoones, due to poor intelligence, failed to pursue retreating Japanese troops from northeastern India, thinking that the Japanese might be planning a counterattack from Tamu and Bishenpur.|
|3 Jul 1944||After sundown, Japanese commandos raided a British airfield near Imphal, India and destroyed eight parked aircraft.|
|4 Jul 1944||General Wazakazu Kawabe officially terminated Operation U-Go in India.|
|7 Jul 1944||Lieutenant General Kotoku Sato was relieved for the defeat at Kohima, India.|
|8 Jul 1944||Lieutenant General Renya Mutaguchi withdrew the remnants of the Japanese 33rd Division from Imphal, India back into Burma.|
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Thomas Dodd, late 1945