This was the Japanese scheme devised by General Heitaro Kimura’s Burma Area Army for the defence of the area around Mandalay and Meiktila in central Burma on the Irrawaddy river (December 1943/March 1944).
Although the Allies expected that the Japanese would attempt to check any Allied offensive from India in an area as far forward as possible, typically along the line of the Chindwin river, Kimura had come to appreciate the implications of the fact that most of the Japanese formations in Burma had been significantly weakened by their heavy casualties during the fighting of the previous 12 months, and were short of equipment and supplies at a time when the Allied forces were becoming more numerous and better supplied, especially with heavier weapons. In order to avoid fighting at a numerical and matériel disadvantage on the Chindwin or in the Shwebo plain between the Chindwin and Irrawaddy rivers, where the terrain provided comparatively few obstacles to the British-led armoured and motorised units, he withdrew Lieutenant General Shihachi Katamura’s 15th Army behind the line of the Irrawaddy river, which it was to hold against Lieutenant General Sir William Slim’s British 14th Army in 'Ban'. Lieutenant General Shozo Sakurai’s 28th Army was to continue to defend the Arakan coastal region of western Burma and also the lower part of the Irrawaddy valley in 'Kan', while Lieutenant General Masaki Honda’s 33rd Army was to prevent the completion of the new road link between India and China by defending the cities of Bhamo and Lashio, and by mounting guerrilla raids in 'Dan'.
The major elements of 'Ban' were known to the British, who therefore undertook the counter-development of their 'Y' (later 'Capital') for a Chindwin offensive into the more ambitious 'Extended Capital' to cut off and destroy the Japanese forces in the Mandalay and Meiktila area.