Bombing of Calcutta

The Bombing of Calcutta was a series of aerial raids carried out by Imperial Japanese Army Air Force on Calcutta, the capital of the British India. The bombing caused significant damages to infrastructure and killed hundreds however it failed to achieve it's primary goal of significantly disrupting allied supply lines.

Background
After the end of rainy season in 1942, the Imperial Japanese Army Air Force became much more active and raided north eastern Assam with the next target of Bombing Calcutta, with the objective of destroying the Calcutta port and delaying the Allied preparations for a counter-offensive. The 7th Air Brigade had been given the responsibility and they had carried out rehearsals in Malaya in November. In late November 1942 the brigade was reinforced by some aircraft of the Imperial Japanese Navy Air Service and, as reconnaissance showed a large concentration of shipping at Calcutta, the Japanese decided to raid the airfields in the Chittagong area at the end of the month to draw the Allied fighters away from Calcutta which was to be attacked on the 5th December but the attack was delayed till December 20.

1942
On December 20, 1942, aircraft of the Imperial Japanese Army Air Force started bombing the city of Calcutta causing damage to infrastructure and multiple casualties. The bombing campaign continued till 24 December. The airstrikes on Christmas Eve were mainly targeting the Europeans but failed to do significant damage and human casualties were not significant. The target Howrah Bridge wasn't damaged but other parts of the city faced damages.

Calcutta had good air defence systems which forced the Japanese pilots to fly high to evade the air defence and they raised Calcutta only during the night. This bombing affected the industrial area and caused the displacement of 350,000 people. United States Army Air Force was also deployed in Calcutta and engaged with the Japanese.

1943
The Royal Air Force bomber responded to these raids by destroying many Japanese aircraft and a Japanese aircraft carrier. By 1943, air defences were strengthened and RADAR guided night fighters were deployed which destroyed several Japanese Mitsubishi Ki-21 and Mitsubishi Ki-46.

In January 1943, multiple Japanese raids were foiled by Royal Air Force.

In August 1943, Royal Air Force deployed Spitfires.

On 5 December 1943, a Japanese bombing on Calcutta's Kidderpore docks caused hundreds of deaths and destruction of several ships and warehouses. Japanese aircraft dropped heavy explosives and anti-personnel bombs on the docks during day, without facing any resistance. The docks were devastated. Royal Air Force warplanes were deployed but they weren't able to engage.

1944
Japanese launched sporadic raids till 1944.

Aftermath
In 1944, due to allied advances on multiple fronts, the Japanese aircraft had to be relocated to other areas for providing support and thus the bombing raids over Calcutta stopped. In 1945, after the Atomic bombings of Hiroshima and Nagasaki, the war came to an end.