The 33rd division was transferred to the 15th army on 6 November 1941, and took part in the invasion of British Burma, under Lieutenant General Shozo Sakurai.

One of its subordinate formations, responsible for the central part of the front facing British India in Nagaland and Assam, was the 15th army, whose new commander was Lieutenant General Renya Mutaguchi.

All Renya Mutaguchi's divisional commanders disagreed with the plan to some extent, and Motoso Yanagida openly derided him as an "imbecile".

The Japanese 215th Regiment under Colonel Masahiko Sasahara captured a supply dump at Milestone 109, twenty miles behind Cowan's leading outposts.

The Japanese 214th Regiment under Colonel Takanobu Sakuma seized Tongzang and a ridge named Tuitum Saddle across the only road, a few miles behind the Indian 17th Division's position.

In early April 1944, the 33rd Division attacked from the south at Bishenpur, where they cut a secondary track from Silchar into the plain.

Although there was now no realistic hope of success, Renya Mutaguchi (and his superior Masakasu Kawabe) ordered renewed attacks.

By 2 June 1944, Renya Mutaguchi's divisional commanders refused to make a renewed attacks on Imphal, as they were in no condition to comply.

The Japanese fell back to the Chindwin River, abandoning their artillery, transport, and soldiers too sick to walk.

When the Allies launched their offensive (Battle of Meiktila and Mandalay) into Central Burma, the Japanese withdrew behind the Irrawaddy River.