Six months after the devastating 1941 attack on Pearl Harbor, Japan sent four aircraft carriers to the tiny Pacific atoll of Midway to draw out and destroy the rest of the U.S. Pacific Fleet.
But this time the United States knew about Japan's plans. U.S. cryptologists had cracked Japanese communications codes, giving Fleet Commander Adm. Chester Nimitz notice of where Japan would strike, the day and time of the attack, and what ships the enemy would bring to the fight.
The U.S. was badly outnumbered and its pilots less experienced than Japan's. Even so, it sank four Japanese aircraft carriers the first day of the three-day battle and put Japan on the defensive, diminishing its ability to project air power as it had in the Pear Harbor attack.
Monday, the current Pacific Fleet commander, Adm. Cecil Haney, and other officials were flying 1,300 miles northwest from Oahu to Midway to mark the 70th anniversary of the pivotal battle that changed the course of the Pacific war.
"After the Battle of Midway we always maintained the initiative, and for the remaining three years of the war, the Japanese reacted to us," Vice Adm. Michael Rogers, commander of the U.S. Fleet Cyber Command, told a crowd gathered outside Nimitz's old office at Pearl Harbor to commemorate the role naval intelligence played in the events of June 4-7, 1942.
Intelligence wasn't the only reason for U.S. victory.
The heroism by dive bomber pilots, Japanese mistakes and luck all played a role. But Nimitz noted that intelligence was critical to the outcome, said retired Rear Adm. Mac Showers, the last surviving member of the intelligence team that deciphered Japanese messages.
"His statement a few days later was, 'Had it not been for the excellent intelligence that was provided, we would have read about the capture of Midway in the morning newspaper,' " Showers said.
Japanese messages were written using 45,000 five-digit numbers representing phrases and words, and the cryptographers had to figure out what the numbers meant without the aid of computers.
"In order to read the messages, we had to recover the meaning of each one of those code groups. The main story of our work was recovering code group meanings one-by-painful-one," Showers said.
Now 92 and living in Arlington, Va., Showers, a native of Iowa City, Iowa, went on to a career in intelligence. He served on Nimitz's staff on Guam toward the end of the war and returned later to Pearl Harbor for stints leading the Pacific Fleet's intelligence effort. After the Navy, he worked for the Central Intelligence Agency.
Showers said commanders weren't always as open to using intelligence to plan their course of attack as Nimitz was. Some were suspicious of it.
But Midway changed that.