I wonder if USA had used chemical weapons, poison gas, like mustard gas and other choking agents, if battle would have been less costly for us. The poison gas would have been very effective at settling into their caves and tunnels unless they had good ventilation systems. We had enormous stockpiles of poison gas, we could have stood off the island and shelled with gas for a week or so, then wait for most of the gas to dissipate before going in with troops. I don’t think japan signed any of the agreements about usage of such weapons. They experimented with plague on our pow’s, they would have had no right to bitch about being gassed.
My father participated in the invasion of the Philippians. He was in MacArthur's Army Air Corp. He came home from there on a hospital ship. After losing all of his top teeth, being shot in the head through the helmet and also in the abdomen.
During the battle he was promoted from Staff Sergeant to Captain because he was the senior enlisted man. All the officers above him were either injured or dead. He was discharged as a Staff Sergeant. He came back home to WNY to farm, eventually marry and have four sons. I was the third. So, I am glad the US did NOT use chemical weapons in WW2.
We actually considered using gas because it was a purely military target.