The Chicago Tribune Incident
In June 1942, after decoding Japanese radio transmissions which revealed their intention to invade and seize the island of Midway in the central Pacific, the United States Navy sent two task forces under the command of Admirals Jack Fletcher and Ray Spruance to ambush the Japanese fleet. The resulting battle of Midway was one of the turning points of World War II, a crushing American victory which saw the loss of four Japanese aircraft carriers to one for the Americans. From that point on the Japanese were on the defensive in the Pacific War. The advantage of being able to read their naval code remained a closely guarded secret.
Before the battle of Midway, the US Navy fought an aerial engagement from the aircraft carriers Lexington and Yorktown with the Japanese fleet in the Battle of the Coral Sea. Present on board Lexington was a reporter for the Chicago Tribune, Stanley Johnston. Lexington was lost during the battle and Johnston and the other survivors were repatriated to the United States. While onboard Lexington, Johnston learned of the American’s ability to decipher the Japanese code, and at some point he saw evidence of the Navy’s foreknowledge of the Japanese plans regarding Midway, including the ships to be involved and the diversionary attack in the Aleutian Islands.
On June 7, 1942, the day following the American victory at Midway, the Chicago Tribune ran a story written by Johnston under the headline, “Navy had Word of Jap Plan to Strike at Sea.” The article provided a detailed rundown of the Japanese ships deployed in the battle and the overall plan of attack, which was a complex battle plan involving strike forces, bombardment forces, invasion forces, and diversionary attacks. From reading the article, which was attributed to “reliable sources” serving in naval intelligence, the obvious inference to be made by the reader was that the Americans were able to read Japanese plans in advance of their execution.
An outraged President Roosevelt, a longtime enemy of Tribune owner Robert McCormick, ordered the prosecution of the newspaper under the terms of the Espionage Act of 1917. Despite pleadings from some in the intelligence community that doing so would increase publicity, the government proceeded to build a case, and in August the Justice Department brought the newspaper before a grand jury, seeking an indictment for publishing information which was an aid to the enemy. There it discovered that prosecuting the Tribune would mean revealing yet more classified information. It also meant that the Tribune would use the First Amendment as its primary defense, ensuring a nationwide story.
In the end the government dropped the case. The attempt to censor the Chicago Tribune and prosecute the paper for revealing classified information was concluded because even if the government had won the case, which is debatable, it risked losing much more. The story was soon replaced with headlines regarding the actions in and around the Solomon Islands. The Japanese either didn’t believe the story or they never heard of it because they did not change the code JN-25 in the aftermath of the Battle of Midway and American and British Intelligence continued to monitor their communications.