Harry S. Truman–Henry L. Stimson relationship

Harry S. Truman and Henry L. Stimson’s relationship became pivotal when the secret atomic-bomb project moved from an obscure item of Senate inquiry to a presidential decision. Stimson, who had overseen the project, offered expert counsel and argued for its use as a means of ending the war; Truman listened, weighed competing options, and retained responsibility for the final choice. Their working relationship also included a notable disagreement over the language of surrender and ended, in public, with Truman honoring Stimson’s service.

Trust before the presidency

As a senator, Truman encountered unexplained expenditures connected with a secret undertaking then identified only as the Manhattan Project. On June 17, 1943, he telephoned Stimson, the Secretary of War, for an explanation. Stimson told him that the matter was known personally to only a handful of people worldwide and was part of a highly important secret development. Truman asked whether it served a specific purpose and whether Stimson considered it proper. Once Stimson assured him that it did, Truman accepted the assurance and made clear that he would ask no more.

The exchange established an important pattern: Truman could insist on knowing that public money served a legitimate purpose without demanding information that Stimson was not free to share. The relationship was neither simple ignorance nor full disclosure. Information continued to reach Truman, and by July he knew the essential nature of the secret development. He even addressed the issue indirectly in a letter to Lewis Schwellenbach, who had asked about enormous land condemnations for the DuPont Company near Hanford. Nearly half a million acres were involved. Truman wrote that Schwellenbach need not worry, while the underlying project remained secret.

A presidential briefing and divided responsibility

Stimson had been involved in the atomic program since November 1941, when Franklin D. Roosevelt appointed him to advise on nuclear fission, and had overseen its development. After Truman became president, Stimson brought him a typewritten memorandum and waited while he read it. Its opening warned that within four months the United States would probably have completed a weapon capable of destroying a city. The briefing also explained that the United States and Great Britain had shared in the work, but that only the United States could then produce the weapon; that advantage was unlikely to last, and Russia might be able to enter production within a few years.

The memorandum made the decision immediate without making it easy. Stimson emphasized that his committee could advise, but that he alone bore responsibility for recommending a course to the President. He argued that a sufficiently powerful shock could compel Japan’s leaders to surrender and, in his judgment, save many more American and Japanese lives than it would cost. Truman therefore received both a description of the weapon’s unprecedented destructive capacity and an explicit account of the reasoning Stimson believed justified its use. The relationship gave the President expert advice, not an escape from judgment.

Invasion plans and the case for use

The atomic question existed alongside plans for an invasion and blockade of Japan. Truman’s diary framed the choice as whether to invade Japan proper or to bomb and blockade it, calling this his hardest decision to date; he did not mention S-1. At a White House meeting on June 18, General George C. Marshall presented a two-phase invasion plan, beginning with Kyushu in November, and estimated that the first thirty days could bring losses similar to those on Luzon, about 31,000. The bomb was not discussed at that meeting, a circumstance that struck John J. McCloy as odd. The record shows that the invasion question and the atomic project were being considered in overlapping but not identical settings.

When Stimson discussed the recommendation with Truman, he conveyed the committee’s view and the position of senior military advisers: the weapon’s shock value, they believed, was necessary to stop the war. A harmless technical demonstration had been considered and rejected. The scientific panel saw no demonstration likely to compel surrender, while uncertainty about whether the first available bomb would work made a failed display especially risky. The advisers’ reasoning was shaped by the ongoing battle for Okinawa, where the scale of American and Japanese losses reinforced the urgency of ending the war. Stimson and Truman’s discussions thus concerned not only the weapon’s power but the uncertain alternatives and the human costs attributed to each.

Potsdam: advice, agreement, and a point of difference

Although Stimson had not been invited to accompany Truman to Berlin, he arranged to go ahead of the President because of the importance of developments concerning S-1. Messages from Washington indicated that the final operation was nearing readiness and that a decision about target cities was required. Stimson urged that Kyoto be removed from the list. Truman agreed, and Kyoto was spared; Hiroshima, a headquarters and depot for Japan’s homeland army, headed the approved list.

Stimson also urged a change to the proposed Potsdam Declaration. He worried that insisting on unconditional surrender could lead Japanese leaders to believe they would lose their Emperor, and proposed language calling for the Allies to continue the war until Japan ceased resisting. James F. Byrnes opposed changing a policy already repeatedly proclaimed, and Truman did not accept Stimson’s proposed revision. This disagreement shows the limits of Stimson’s influence: he could put an alternative before the President, but did not determine the policy. Truman listened carefully while retaining the established demand.

On July 23, Stimson brought Truman a top-secret message reporting when the operation might be possible, depending on preparations and conditions. Stimson later recorded that Truman welcomed the news. Truman subsequently recalled a consensus among Stimson, Byrnes, William D. Leahy, Marshall, and General Arnold that the bomb should be used, and cited Marshall’s estimate that an invasion could cause at least a quarter of a million American casualties. The record does not establish one unmistakable instant when Truman decided. The decisive discussion appears to have taken place on July 24, when Truman and Winston Churchill met with the combined American and British Chiefs of Staff; later that day Truman told Joseph Stalin that the United States had a new weapon of unusual destructive force. Stimson’s counsel formed part of the deliberations, but Truman later insisted that the final decision about where and when to use the bomb was his.

Retirement and public recognition

The relationship concluded in a formal act of recognition. On September 21, at a small gathering in the Rose Garden, Truman presented Stimson with the Distinguished Service Medal on the day of Stimson’s retirement and seventy-eighth birthday. Truman’s letter to Bess described Stimson as deserving of the medal. The occasion suited Truman’s manner: he was particularly effective in small ceremonies where he could convey the significance of an honor directly.

Truman later remembered Stimson as a man who was honest, straightforward, and genuinely a statesman. That assessment fits the relationship recorded across their exchanges: Stimson supplied guarded information, a grave warning, and sustained advice; Truman offered trust, listened to arguments, accepted some recommendations, rejected another, and carried the final burden himself. Their association mattered not because they agreed on every point, but because the secrecy and stakes of the atomic decision required candid counsel within a relationship that still left presidential responsibility unmistakably with Truman.