PEARL HARBOR, Hawaii - The Navy’s Pacific Fleet commander, Admiral Cecil Haney, and other officials flew 1,300 miles from Oahu to Midway on Monday to mark the 70th anniversary of the pivotal battle that changed the course of the Pacific war.

Japan sent four aircraft carriers to the tiny Pacific atoll of Midway six months after the attack on Pearl Harbor. Their mission was to draw out and destroy what remained of the US Pacific Fleet. But this time the United States knew about Japan’s plans. US cryptologists had cracked Japanese communications codes, giving Fleet Commander Admiral 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 United States 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, greatly diminishing its ability to project air power as it had in the attack on Hawaii.

“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 Admiral Michael Rogers, commander of the US Fleet Cyber Command, told a crowd at Pearl Harbor on Friday to commemorate the role naval intelligence played in the events of June 4-7, 1942.

“It all started really in May of 1942 with station Hypo [the Combat Intelligence Unit at Pearl Harbor] and the work of some great people working together to try to understand what were the Japanese thinking, what were they going to do,’’ Rogers said.

Intelligence wasn’t the only reason for US victory.

The heroics by dive bomber pilots, Japanese mistakes, and luck all played a role. But Nimitz himself observed it was critical to the outcome, said retired Rear Admiral 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 in an interview.