The Japanese soldiers had CYANIC GAS GRENADES on some of the Pacific Islands but did not use them. I’ve found scattered documents at the National Archives, College Park, Md, that talked about them and had a few photos of these glass-globe cyanide grenades.
They should be in Record Group 175 - Chemical Warfare Service records. My father was in the CWS, helping test the 4.2 Chemical (WP) mortar at Edgewood Arsenal/Aberdeen Proving Group. He also worked on gas mask preparations. If the Japanese had used gas warfare during the last few months of the Pacific campaigns, he would have been sent to Australia to help supervise the stockpiling of our own gases, usually Mustard, to be used in retaliation.
Fortunately gas was not used by any side.
During the war he assembled aircraft shipped to England.
After the end of the war he was put to work disposing of Chemical Weapons that had been stockpiled for use in the war if needed while he waited to be shipped home.
During that work one of the bombs leaked in to the mud beneath the bomb racks.
He stepped in the mud and it soaked his boots. I believe he told me the bombs held phosgene gas.
His feet began to swell and later the skin came off in strips.
For decades after the perspiration from his feet would quickly rot his leather boots in a matter of months