The Magazine

Why Truman Dropped the Bomb

From the August 8, 2005 issue: Sixty years after Hiroshima, we now have the secret intercepts that shaped his decision.

Aug 8, 2005, Vol. 10, No. 44 • By RICHARD B. FRANK
Widget tooltip
Single Page Print Larger Text Smaller Text Alerts

All of this effort and expertise would be squandered if the raw intercepts were not properly translated and analyzed and their disclosures distributed to those who needed to know. This is where Pearl Harbor played a role. In the aftermath of that disastrous surprise attack, Secretary of War Henry Stimson recognized that the fruits of radio intelligence were not being properly exploited. He set Alfred McCormack, a top-drawer lawyer with experience in handling complex cases, to the task of formulating a way to manage the distribution of information from Ultra. The system McCormack devised called for funneling all radio intelligence to a handful of extremely bright individuals who would evaluate the flood of messages, correlate them with all other sources, and then write daily summaries for policymakers.

By mid-1942, McCormack's scheme had evolved into a daily ritual that continued to the end of the war--and is in essence the system still in effect today. Every day, analysts prepared three mimeographed newsletters. Official couriers toting locked pouches delivered one copy of each summary to a tiny list of authorized recipients around the Washington area. (They also retrieved the previous day's distribution, which was then destroyed except for a file copy.) Two copies of each summary went to the White House, for the president and his chief of staff. Other copies went to a very select group of officers and civilian officials in the War and Navy Departments, the British Staff Mission, and the State Department. What is almost as interesting is the list of those not entitled to these top-level summaries: the vice president, any cabinet official outside the select few in the War, Navy, and State Departments, anyone in the Office of Strategic Services or the Federal Bureau of Investigation, or anyone in the Manhattan Project building the atomic bomb, from Major General Leslie Groves on down.

The three daily summaries were called the "Magic" Diplomatic Summary, the "Magic" Far East Summary, and the European Summary. ("Magic" was a code word coined by the U.S. Army's chief signal officer, who called his code breakers "magicians" and their product "Magic." The term "Ultra" came from the British and has generally prevailed as the preferred term among historians, but in 1945 "Magic" remained the American designation for radio intelligence, particularly that concerning the Japanese.) The "Magic" Diplomatic Summary covered intercepts from foreign diplomats all over the world. The "Magic" Far East Summary presented information on Japan's military, naval, and air situation. The European Summary paralleled the Far East summary in coverage and need not detain us. Each summary read like a newsmagazine. There were headlines and brief articles usually containing extended quotations from intercepts and commentary. The commentary was critical: Since no recipient retained any back issues, it was up to the editors to explain how each day's developments fitted into the broader picture.

When a complete set of the "Magic" Diplomatic Summary for the war years was first made public in 1978, the text contained a large number of redacted (literally whited out) passages. The critics reasonably asked whether the blanks concealed devastating revelations. Release of a nonredacted complete set in 1995 disclosed that the redacted areas had indeed contained a devastating revelation--but not about the use of the atomic bombs. Instead, the redacted areas concealed the embarrassing fact that Allied radio intelligence was reading the codes not just of the Axis powers, but also of some 30 other governments, including allies like France.

The diplomatic intercepts included, for example, those of neutral diplomats or attachés stationed in Japan. Critics highlighted a few nuggets from this trove in the 1978 releases, but with the complete release, we learned that there were only 3 or 4 messages suggesting the possibility of a compromise peace, while no fewer than 13 affirmed that Japan fully intended to fight to the bitter end. Another page in the critics' canon emphasized a squad of Japanese diplomats in Europe, from Sweden to the Vatican, who attempted to become peace entrepreneurs in their contacts with American officials. As the editors of the "Magic" Diplomatic Summary correctly made clear to American policymakers during the war, however, not a single one of these men (save one we will address shortly) possessed actual authority to act for the Japanese government.