The Battle of Midway (Pivotal Moments in American History) (22 page)

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Dwight Morrow, a former Republican senator from Ohio, had a special interest in aviation. (His daughter Anne would later marry the famed aviator Charles Lindbergh.) It was the Morrow Board that recommended the creation of a separate Air Corps within the U.S. Army.

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The Army pilots were Lieutenants John Fitzgerald and James McCarthy, the first men to fly land-based bombers off a carrier deck, and they did so with no special training and very little advance notice.

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Very likely, Captain York’s plane burned fuel faster than the others because the mechanics at McClellan Field near Sacramento, unaware that the carburetors on the Mitchell bombers had been specially recalibrated for fuel economy, reset them to normal.

7

The Code Breakers

I
n addition to the men who drove the ships, flew the planes, or manned the guns—and those who some months later waded ashore carrying M-1 rifles—there were others whose contributions to victory in the Pacific were of an entirely different sort. Among the most consequential were those whose job it was to intercept, decrypt, and analyze Japanese radio traffic. In a windowless basement room at Pearl Harbor officially dubbed the Combat Intelligence Unit and which those working there called “the dungeon,” more than two dozen men toiled around the clock in an effort to glean useful intelligence out of the Japanese radio messages that were plucked out of the ether every day by the radio receiver at He’eia on Oahu’s north shore. It was the most secret organization in the U.S. Navy. Some of these men (called the “on-the-roof gang,” or “roofers” in the workplace vernacular) wore headsets and transcribed the blizzard of dots and dashes into number groups or Japanese kana characters.
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Others sought to find patterns in those characters by running primitive IBM card-sorting machines that spewed out millions of punch cards each day. Still others sat at desks or tables and worked through tall stacks of intercepts, looking for repeated codes or phrases that might provide a hint about Japanese movements or intentions. It was an eclectic team of idiosyncratic individuals that collectively played one of the most important roles in the Pacific War, and particularly in the Battle of Midway.
¹

As far back as World War I, the United States had been successful at breaking the Japanese diplomatic code. In the 1920s, a clandestine organization headed by Herbert Yardley and rather dramatically dubbed “the Black Chamber” devoted itself to breaking the diplomatic codes of several nations, including Japan. Their success had allowed the Americans to take a hard line at the 1921–22 Naval Arms Limitation Conference in Washington, where they had proposed that 10:10:6 ratio in battleship tonnage for the United States, Great Britain, and Japan. Though the Japanese were holding out for a 10:10:7 ratio, the American chief negotiator—the secretary of state and future Supreme Court chief justice Charles Evans Hughes—knew from reading intercepted Japanese secret messages that Tokyo would accept the 10:10:6 formula rather than let the talks fail.

Six years later, when the State Department was preparing for the London Naval Conference, Yardley sent President Hoover’s new secretary of state, Henry Stimson, a batch of decrypted messages that revealed Japan’s negotiating strategy. Instead of praising Yardley, Stimson was horrified. He was said to have remarked that “gentlemen do not read other gentlemen’s mail.” Whether or not he actually made this statement, he shut down the Black Chamber and ended, temporarily, efforts to read Japanese diplomatic messages. Yardley, who apparently could not resist claiming public credit, got even with Stimson a few years later by exposing the operation he had led in a series of magazine articles, and then by publishing a memoir,
The American Black Chamber
(1931), in which he revealed the once highly secret operation. For their part, the Japanese complained that the Americans had been cheating and resolved to improve their codes.
²

The U.S. Navy was less fastidious than the State Department; efforts to break the Japanese Navy’s operational code continued uninterrupted. This quite separate effort began in 1924, when the communications intelligence organization was established on the top floor of the Navy Department building in Washington under the Code and Signals Section. Placed under the director of Naval Communications, this office was designated as OP-20-G. For almost twenty years, OP-20-G was the private fiefdom of the gifted and eccentric Commander Laurance F. Safford, a lugubrious, bespectacled 1916 Annapolis graduate with darting eyes and disheveled hair who looked, one coworker said, as if “he had been scratching his head in perplexity.”
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It was Safford who established the unit’s two satellite stations, one in Manila in 1932 called Station Cast, and Station Hypo in Hawaii in 1936.
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It was also Safford who recruited the first team of analysts who became key players in the wartime code-breaking effort.
**

One of those whom Safford recruited was Ensign Joseph J. Rochefort, who had enlisted in the Navy in the last days of World War I and earned a commission after graduating from Stevens Institute. Rochefort was a tall, thin, and soft-spoken man whose ready smile disguised a fierce intensity. He had not set out to be a code breaker, and never requested the duty. Nevertheless, in 1924 his former commanding officer on the fleet oiler
Cuyama
, Commander Chester Jersey, when asked to nominate someone for the Code and Signals Section, recalled that Ensign Rochefort had been particularly good at crossword puzzles. He sent in Rochefort’s name, and in 1925 Ensign Rochefort became Safford’s number two man. Four years later, the Navy sent Rochefort to Japan for a three-year tour, ostensibly as an attaché but really to study Japanese language and culture.
⁴

Joe Rochefort, seen here as a captain in a postwar photograph, was a key figure in the American code-breaking apparatus before and during the Battle of Midway. (U.S. Naval Institute)

Both Safford and Rochefort proved adept at the tedious and exacting work of code breaking, but they could not remain continuously in the job. Because the Navy expected its officers to serve at sea if they expected to be promoted, the two men adopted the practice of filling in for one another: Rochefort took over OP-20-G when Safford went to sea, and Safford resumed command when it was Rochefort’s turn to deploy. In June of 1941, with war looming, Safford sent Rochefort, by now a lieutenant commander, out to Hawaii to take over as the head of the Combat Intelligence Unit (CIU), colloquially known as Station Hypo. There, Rochefort had particular responsibility for breaking what was called the “Japanese admirals’ code.” Station Cast in Manila remained focused on trying to decrypt the Japanese Navy’s operational code.
⁵

As it happened, the Japanese made little use of the admirals’ code, and for several months—including the critical month before Pearl Harbor—Rochefort and his team spent a lot of time chasing down blind alleys. Since they did not have access to the intelligence gathered from either the Japanese diplomatic code (known as “Purple”) or the operational codes, Rochefort could not share information gathered from those sources with his boss, Admiral Kimmel.
⁶

Instead, Rochefort and his team relied heavily on traffic analysis, that is, an examination of the external character of the messages rather than of their content. The analysts noted the call sign, the message classification, its level of importance or precedence, the frequency of transmission, its length, and the location of the transmitter to draw conclusions about what the message might mean in terms of Japanese naval movements. If, for example, the volume of message traffic suddenly surged, it could mean that a fleet was getting under way. Of course, since fleets at sea often maintained radio silence, the
absence
of radio traffic might be equally significant. When messages to or from the Kidō Butai suddenly stopped, that could be as important as a sudden flurry of messages, or even more important. In addition, it was occasionally possible for a veteran operator at He’eia to determine the identity of the sender of a particular message by recognizing the characteristic tempo or cadence (called a “fist”) of his Morse-code transmissions. If the sender was known to work at a specific base or ship, it provided the Americans with one more piece of intelligence. Traffic analysis had limitations, however. On one occasion, when radio traffic showed that several destroyers usually associated with a particular Japanese carrier were in the Marshalls, Rochefort assumed the carrier was there, too. He was wrong. His rare error was an example of how the analysts had to apply intuition to determine the utility of the intercepts.
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None of this, of course, helped the Americans predict the attack on Pearl Harbor, and after December 7 it seemed to many that a housecleaning was in order. Just as Kimmel was shoved aside in Hawaii, Safford was replaced at OP-20-G by Captain John R. Redman. A member of the Naval Academy class of 1919 who had graduated early for service in World War I, Redman had excelled in athletics. A standout on the football and lacrosse teams, he was also captain of the wrestling team, a sport in which he competed at the 1920 Olympic Games in Antwerp, finishing fourth as a light heavyweight and just missing an Olympic medal. Redman had a strong personality and long service as a communications officer in cruisers and battleships, but no real experience or expertise in code breaking. In fact, his prime qualification for his new job may have been that his older brother, Rear Admiral Joseph R. Redman, was the director of Naval Communications.

Captain John Redman, seen here as a rear admiral in a postwar photograph, headed up the intelligence office in Washington (OP-20-G) and was often suspicious of Rochefort’s analysis. (U.S. Naval Institute)