A number of parallels have been drawn between Pearl Harbor and 9/11 - both were rare attacks on American soil, both launched the U.S. into war, each has its own set of conspiracy theories.

And retired University of Florida Professor Michael Gannon, a noted Pearl Harbor historian, said some of the shortcomings in the U.S. defense system that led to the Japanese bombing of the Hawaiian base 66 years ago today could teach current political and military leaders some lessons.

"Pearl Harbor is a lesson in preparedness and it is a lesson, also, in . . . letting down its officers in the field," Gannon said. "The tragedy . . . on 9/11 has been generally perceived by the American people as worse than what happened in Pearl Harbor. The destruction was greater than the military losses in Pearl Harbor. In terms of loss of life is concerned, they were pretty much the same."

Japan bombed a U.S. Navy base at Pearl Harbor on Dec. 7, 1941, catching the government and top military leaders in Washington off guard.

Gannon is author of "Pearl Harbor Betrayed: The True Story of a Man and a Nation under Attack."

He contends that President Franklin Roosevelt and top brass were so focused on going to war with Germany that Pearl Harbor was left with few defenses.

When Japan attacked, 2,323 Americans were killed and several ships were sank. Most of the ships were refloated, repaired and used later in the war, Gannon said.

The psychological impact of the attack was almost as visceral as the physical attack.

"The effect was very severe. It was a humiliating defeat, as Americans looked on it, and one of the slogans that developed was 'Remember Pearl Harbor.' It was a very powerful slogan or war cry," Gannon said.

"In the view of the American people, that was a defeat that just had to be avenged."

Gannon and others say that the cultural relevance of Pearl Harbor to the general public is fading as time passes and new events occur...