Mutaguchi was then made commander of the Fifteenth Army from March 1943, and strongly pushed forward his own plan to advance into Assam, leading to the Battle of Imphal. After the failure of the Imphal offensive in May 1944, Mutaguchi refused to allow his divisional commanders to retreat, and instead dismissed all three of them. He eventually called off the attack on 3 July. Some 55,000 of Mutaguchi's 85,000-man force ended up as casualties, many dying from starvation or disease. This was the worst defeat to that time suffered by the Japanese army. With the complete collapse of the offensive, Mutaguchi was relieved of command on 30 August and recalled to Tokyo. He was forced into retirement in December 1944.