Why We Didn’t Use Poison Gas in World War II


If he had wanted to, could Truman have reversed Roosevelt’s public commitment? What tactics might he have successfully employed? He could have lied and claimed publicly that Japan had recently initiated gas warfare and that the United States was only retaliating. But such deceit could have backfired and would have been politically risky. As a top-secret Army report warned, “the probability that our decision to adopt gas warfare could be long hidden under the cloak of a framed incident is small.”


And despite the optimism of Army planners about public opinion, an open presidential admission of a policy reversal would also have been politically dangerous. The American people, though inured to the intentional killing of civilians by bombing, might still have protested against gas. For years it had been condemned as immoral, and throughout the war most nations—including Germany—had seemed to abide by that ethical code in combat.

By mid-1945 the injury to American prestige and power would not have been worth the military advantages of violating the accepted morality. Perhaps if a handful of respected advisers all had argued the necessity of a reversal, Truman might have changed policy. But not even Marshall argued for the necessity of gas warfare; he only said it would be useful. Finally, it would have been difficult for Truman to justify a rejection of FDR’s public pledge. Whereas Roosevelt was an architect of the use of the atomic bomb, he was a powerful opponent of gas warfare. In each case FDR’s legacy, carried in part by the advisers he had bequeathed to his successor, narrowed the range in which the new President could make decisions. And in each case that legacy probably also fitted Truman’s own inclinations.

Yet any analysis of this question of what might have been is, to use FDR’s word, iffy. Had the Pacific war dragged on into the late autumn and winter, Truman might have been under growing pressure to use gas against the hated Japanese. The costly struggle was eroding American repugnance to gas, and future battles in Japan, with thousands of GI deaths, might well have led American citizens to push their government to use gas warfare. Under those pressures only a secure and powerful President like FDR, with a firm commitment against gas, might have chosen to resist. Truman, less secure and not wedded to that commitment, might have yielded more easily, especially after the atomic bombings. Truman later wrote, “The Atomic bomb … is far worse than gas or biological warfare because it affects the civilian population and murders them wholesale.”

And in his last years Truman kept on his bookshelf, next to volumes about the A-bomb decision, a copy of Hamlet, with Horatio’s speech in the last act underlined:

let me speak to the yet unknowing world How these things came about: so shall you hear Of carnal, bloody, and unnatural acts, Of accidental judgements, casual slaughters, Of deaths put on by cunning and forced cause, And, in this upshot, purposes mistook Fall’n on the inventor’s heads. … But let this same be presently perform’d, Even while men’s minds are wild; lest more mischance, On plots and errors, happen.