Why did Japan wait until 1944 before they started a large offensive in to India?

Why did Japan wait until 1944 before they started a large offensive in to India?
Since it was allready clear that Japan and Germany were losing important battles in 1943, and British India was important, a succesfull invasion of India was their only chance to change the course of the war.


The Japanese had reached the end of their logistical tether by late 42/early 43 in Burma. They’d had excellent results pushing back both British and Chinese forces in every campaign, but usually with fewer troops and shoestring supplies. It wasn’t until 1944 that IJA leadership freed up enough resources from other fronts to make another push out of Burma and the lines of easy transportation (such as they are) run vaguely northeast to southwest, almost literally at right angles to the lines of advance for armies of both Japan and Britain.

I suspect the IJA also expected much better results from the Indian National Army and clandestine fifth-column support in India proper when the campaign kicked off. Bose may have over-promised, but the IJA believed him.

Logistics are important in every military campaign, but logistics in Burma were perhaps the worst problem any set of opposing armies faced during the entire war aside from the German 6th Army trapped in Stalingrad. The road net in Burma was very limited and at least until late 1943 the British/Indian/Commonwealth forces were far too dependent on road transport, while the Japanese began the campaign with very few motorized units (they captured a lot during the war, but they didn’t get as much benefit from them because the roads were still too primitive).

A successful invasion of India from Burma would have been a huge political victory, but I very much doubt that it would have gotten very far militarily even if the Japanese had prevailed at Imphal-Kohima, without a substantial naval campaign (which Japan no longer had the resources to do). Part of the reason the British hadn’t launched many assaults into Burma was that the road and rail net from the rest of India to the frontier wasn’t much better than the roads in Burma proper. Vast resources were poured into Assam to upgrade the road, railway, and air transport links, but the work went slowly due to limited equipment being supplied from outside India.