The end of Japanese raids on Calcutta

Some war chronologies place the end of the Japanese air raids on Calcutta under 30 December 1943. The date needs explaining. None of the known sources records a raid on 30 December, or any decision that ended them. The last large attack on the city had come 25 days earlier, on 5 December, when Japanese army and navy aircraft bombed the Kidderpore docks on the Hooghly in broad daylight. According to the American air historian Richard L. Dunn, the Japanese repeated no such expedition in December 1943 or January 1944, and afterwards their aircraft were needed on other fronts. Isolated, minor attacks still occurred, according to Indian studies, until December 1944. The date of 30 December is thus a conventional close to the year in which Calcutta suffered its heaviest raid of the whole war.

A year’s respite

The first series of night raids on Calcutta, in December 1942, did little damage but caused hundreds of thousands of inhabitants to flee. In January 1943 Bristol Beaufighter night fighters with airborne radar arrived in the city and were formed into No. 176 Squadron RAF. Its pilots, among them Sergeant Maurice Pring, shot down several Japanese bombers, and the Japanese army air force gave up its night raids. For most of 1943 only reconnaissance aircraft appeared over Calcutta.

In the meantime the city’s importance grew still further. The port on the Hooghly was the main supply gateway for British troops on the Burmese frontier, for the Americans building the Ledo Road and for the airfields in Assam from which transport aircraft carried cargo over the Himalayas to China. Around Calcutta were the bomber bases of Eastern Air Command, which from 25 November had been conducting a joint offensive with the RAF against Rangoon. The same rail and port network also served a province stricken by the Bengal famine, in which, according to various estimates, between 2 and 3 million people died; in the autumn of 1943 people who had come in from the countryside in search of food were dying in the streets of Calcutta.

The air defences were no longer what they had been a year earlier. In the autumn of 1943 the first Spitfire fighters reached India, and in November they shot down several Japanese reconnaissance aircraft over Bengal. At the end of November, however, they were moved forward to airfields around Chittagong, and the city itself was defended mainly by pilots flying Hurricanes.

The raid of 5 December

The Japanese command in Burma decided to strike at the port through which the Allies’ supplies passed. The operation was prepared jointly by the army’s 5th Air Division and the navy’s newly formed 28th Air Flotilla, whose fighters were based in Sumatra and at Port Blair in the Andamans. On the morning of Sunday 5 December the aircraft assembled over Magwe in central Burma. The first wave consisted – 18 according to Japanese documents, 26–27 according to an intercepted signal and British observations – of Mitsubishi Ki-21 bombers of the 12th and 98th Air Regiments, escorted by about 75 Nakajima Ki-43 fighters. Behind them flew the navy wave: nine Mitsubishi G4M bombers of the 705th Air Group, one of which turned back, and 27 Mitsubishi A6M fighters of the 331st Air Group.

The force flew over the sea, a few kilometres offshore, to avoid the airfields around Chittagong, while reconnaissance aircraft scattered strips of foil to jam British radar. Spitfires from three squadrons and Hurricanes from four more were scrambled, but only a few caught up with the enemy. At about midday local time the first wave dropped its bombs on the Kidderpore docks in the southern part of Calcutta, and roughly an hour later the navy bombers arrived. It was the first daylight raid on the city.

Over Calcutta Hurricanes of Nos. 67 and 146 Squadrons RAF attacked the first wave, but the Japanese fighters kept them away from the bombers. Several aircraft of No. 176 Squadron were sent against the returning navy formation; before they could reach the bombers, Zeros fell on them from above. Maurice Pring, by now a Flying Officer and the hero of the city’s defence a year earlier, was killed, along with one other pilot. According to an Allied intelligence report compiled after the raid, the RAF lost five fighters missing and five crashed, while the Japanese lost one bomber and one fighter shot down; Japanese records show that they lost only one bomber. The air battle had clearly been lost by the defenders.

The damage in the port

High-explosive and anti-personnel bombs hit warehouses, quays, railway tracks and a barrage balloon site. More than a dozen barges were burnt out, a floating crane was damaged, and so, according to the British Admiralty, were eight merchant ships, including the American William Whipple, which was unable to sail with her convoy. Most of the victims were dock workers, especially porters sleeping in huts beside the docks. The Government of India announced 167 civilians killed and 435 injured; other estimates speak of 335 to about 500 killed, and some accounts put the total number of casualties, including the injured, at 500. According to military reports four British servicemen and one American were also killed, and several dozen wounded.

For the course of the war the economic effect proved more important. As a year earlier, the workers fled the port: on 7 December only about a tenth of the usual 4,000–5,000 men were working on the quays, and soldiers took over some of the work. Ten days after the raid the port was operating at two-thirds of capacity. Over the whole of December cargo handled at Calcutta was a third lower than usual, and American forces in India received about 15,000 tons less in supplies than planned. Dunn observes that a series of such attacks could have seriously hampered the American offensive in northern Burma and the supply of China by air.

Why the raids stopped

Despite this success the Japanese did not return over Calcutta in similar strength. There were several reasons. An expedition at the limit of range required assembling almost the entire air force in Burma together with help from the navy, and the aircraft could carry only light bomb loads. On the Allied side Spitfires, radars and airfields were multiplying, and American and British bombers were attacking Japanese bases in Burma. Above all, though, Japan needed its aircraft elsewhere. At the turn of 1943 and 1944 the American offensives in the Central and South-West Pacific were drawing in more and more Japanese air units, and according to British studies most of the air force in Burma was transferred to other fronts in January 1944. From then on the enemy was unable to pose a serious threat to Calcutta.

The date of 30 December comes from English-language chronologies of the war, which at this point sum up the year rather than describe a specific event. British, American and Japanese sources contain no trace of either a raid or an order on that day. It is therefore more accurate to say that the serious raids ended in December 1943, while isolated, infrequent attacks on Calcutta and its surroundings continued into 1944; according to the Indian website Bharat Rakshak the last of them came on Christmas Eve 1944.

Place in the history of the war

The raid of 5 December was the last major success of Japanese air power over India. It showed that Calcutta, on which the supply of the whole Burma front and of the airlift to China depended, was still vulnerable, and it hastened the strengthening of its defences. For South East Asia Command under Admiral Louis Mountbatten, set up in the autumn of 1943, it was also a lesson: without command of the air over Bengal and Burma no offensive could be conducted. In the same weeks the Chinese troops of General Joseph Stilwell were entering the Hukawng Valley, and the Japanese symbolically handed the Andamans over to the Azad Hind government – the very islands from which navy fighters had escorted the expedition against Calcutta.

In 1944 air superiority passed decisively to the Allies. When the Japanese attacked India in the spring, transport aircraft from airfields in Bengal and Assam supplied the encircled troops in the battles of Imphal and Kohima, and the Japanese air force could do nothing to stop them. Calcutta became one of the largest rear bases of the war in Asia, with airfields, depots and a port working for the Burma front and for China. For its inhabitants, however, 1943 remained above all the year of the famine, which killed far more people in Bengal than all the Japanese raids put together.