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


His advisers had also considered bacteriological warfare —probably anthrax, code-named “N.” It “is the only Allied biological agent,” the Joint Planning Staff, advisers to the British military chiefs, reported, “which could probably make a material change in the war situation before the end of 1945. There are indications which lack final scientific proof, that the 4-lb. bomb charged with 'N,’ used on a large scale from aircraft might have a major effect on the course of the war.” The Joint Planning Staff concluded that Britain, dependent on the United States for “N,” would still lack adequate stocks of it well into 1945. Had supplies been ample, however, Churchill might have faced a tempting military prospect.

In the United States, a relatively powerless group, seeking to halt Hitler’s relentless gassing of Europe’s Jews as part of the “final solution,” urged Roosevelt to threaten Hitler with gas warfare if Germany did not stop its program. These petitions predictably failed. The Joint Chiefs, to whom the pleas were sent, concluded the matter was not in “their cognizance.” And Hitler never used gas against Allied armies, probably because he feared retaliation and recalled his own gassing of 1918.

Despite Roosevelt’s pledge against gas, the United States Army hoped in 1945 to initiate gas warfare against Japan. On several occasions Gen. George C. Marshall, Army chief of staff, wanted to use it in the Pacific. The first time, after the heavy casualties at Iwo Jima in February and March, Marshall proposed using the weapon on Okinawa before the invasion, then deemed likely to cost thousands of American casualties. Gas warfare, as Marshall later explained, would have pushed the inhabitants to a remote part of the island and kept the Japanese troops in gas masks for about a week, thus so weakening them that the invasion “could have been accomplished with little loss of life.” In recalling these plans, Marshall never mentioned that gas was inhumane. His implication seemed clear: The efforts to save American lives overrode the constraints of morality.

Why, then, wasn’t the gas used? Marshall later claimed that the chief reason was the opposition of the British, who feared that Germany, caught in the last weeks of war, might use the weapon in Europe. Marshall implied that Roosevelt might have repudiated his pledge and sanctioned America’s initiation of gas warfare. There are no records of any conversation with Roosevelt on this matter, however, and probably Britain’s fears sufficed to deter Marshall from raising the issue with FDR in the early spring of 1945.

With the defeat of Germany on May 8, such fear of retaliation in Europe evaporated. Accordingly Gen. Joseph Stilwell, the former commanding general of Army ground forces in China, recommended, only a few weeks after President Roosevelt’s death, that gas be used in the invasion of Japan. Disregarding Roosevelt’s repeated and adamant public statements, Stilwell said, “We are not bound in any way not to use it, and the stigma of using it on the civilian population can be avoided by restricting it to attack on military targets.”

At a special session on May 29 with Secretary of War Stimson, according to a recently declassified document, General Marshall pushed for gas “to cope with the … last ditch defense tactics of the suicidal Japanese.” Appalled by American casualties in the battles on the outlying islands, Marshall argued the case for gas warfare: “It did not need to be our newest and most potent—just drench them and sicken them so that the fight would be taken out of them—saturate an area, possibly with mustard. …”

He admitted that public opinion might be a problem but concluded that it could be dealt with. After all, he argued, gas was “no less inhumane than phosphorus and flame throwers and need not be used against dense populations or civilians—merely against these last pockets of resistance which had to be wiped out but had no other military significance.”

Had the Pacific war dragged on, Truman might have been pressed to use gas against the Japanese.

The issue did not dominate this May 29 meeting, however, for Stimson and Marshall were primarily concerned with the use of the atomic bomb. Marshall, while willing to violate the moral code against gas warfare, was reluctant to use the bomb against civilians. He recommended that it “might first be used against straight military objectives such as a large naval installation and then if no complete result was derived from the effect of that… we ought to designate a number of large manufacturing areas from which the people would be warned to leave—telling the Japanese that we intended to destroy such centers.”

Just two days later, however, the Interim Committee, a high-level advisory group on the A-bomb, “agreed that the most desirable target would be a vital war plant employing a large number of workers and closely surrounded by workers’ houses.” This would be, in effect, terror bombing—with mass deaths designed to frighten the living into surrendering before they suffered a similar fate.