chemical weapons were not used very much in world war ii, except by the japanese army during the invasion of china. this was because everybody was afraid that the other side would use weapons like theirs. also, chemical weapons were not easy to use. they took time to use, and this made it harder for soldiers to move quickly. also, the raw materials needed to make chemical weapons were not easy to get. this was because world war ii was fought in areas which were not connected well by railroads.