 The operation started May 15, 1942, with 40 infantry battalions and 15–16 artillery battalions but was repelled by Chinese forces in September.During this campaign, the Imperial Japanese Army left behind a trail of devastation and also spread cholera, typhoid, plague and dysentery pathogens.Chinese estimates allege that as many as 250,000 civilians, the vast majority of whom were destitute Tanka boat people and other pariah ethnicities unable to flee, may have died of disease.