The bombing pushed the U.S. into World War II, marking a fundamental change in U.S. foreign policy.
This year's memorials will be somber for another reason: the number of witnesses to the Pearl Harbor attacks is shrinking.
The memories of Dec 7, 1941 are etched in the minds of those who survived.
"It was just a tremendous amount of explosions, then the smoke, and a little later on, the fire on top of the water," said Mal Middlesworth, a Marine veteran who was on the USS San Francisco during the bombing.
The bombing was a surprise. Early on a Sunday morning, Japanese fighter jets swooped in, and when it was over, some 2,400 American lives had been lost.
"I was so shocked. I didn't really have much of a feeling. Afterwards, it haunted me," said David Callahan of Citrus Heights, Calif.
About 120 survivors joined Navy Secretary Ray Mabus, military leaders and civilians to observe a moment of silence in Pearl Harbor at 7:55 a.m. Hawaii time - the moment the attack began seven decades ago.
About 3,000 people were expected at the event held each year at a site overlooking the sunken USS Arizona and the white memorial that straddles the battleship.
Wednesday is the last time the anniversary will be commemorated with the Pearl Harbor Survivors Association. The group is disbanding at the end of the month.
With fewer survivors still alive, those who are left worry that the reality of the attack will die with them.
"There's only about a half-page in a history book about Pearl Harbor, and half of that half-page is a picture of the [USS Arizona]. So our youngsters don't understand what really happened. They don't understand that freedom isn't free," said Middlesworth.
A memorial ceremony also was set to be held Wednesday in Norco, Calif., at the Lake Norconian Club. A half-dozen Pearl Harbor survivors were expected to join hundreds of veterans at the event.
The Associated Press contributed to this report.
