A week after Japan bombed Pearl Harbor on Dec. 7, 1941, Secretary of the Navy Frank Knox returned from an inspection tour of Hawaii and told a shaken nation that "the most effective fifth-column work of the entire war" had aided the surprise attack.

Using a term Americans associated with disloyalty, subversion and collaboration with the enemy, Knox blamed it on those of Japanese ancestry living in Hawaii. They were accused in widely publicized rumors of signaling the Japanese fleet or cultivating pineapple fields in the shape of arrows pointing to Pearl Harbor.

The media gave the fifth-column charge legitimacy and turned against Japanese Americans on the mainland. "The fifth-column problem," Walter Lippmann wrote after being briefed by military officials, ". . . is very serious and it is very special . . . . The Pacific Coast is in imminent danger of a combined attack from within and without." The U.S. military cited this threat to the West Coast to justify drastically restricting the freedom of Japanese Americans living there.

The Supreme Court also used the term "fifth-column" in approving the action. But there never was any truth to it. Not a single example of espionage or disloyalty by a Japanese American was ever documented during World War II. Government officials up to President Roosevelt received intelligence reports specifically refuting the fifth-column charge.

Yet they never publicly disavowed it. Instead, they allowed 120,000 Japanese Americans to be interned in remote camps behind barbed wire throughout the war without attempting to determine whether any individual was guilty of disloyalty.

"We came to the conclusion that they had to be dealt with as a group," John J. McCloy, who was assistant secretary of war at the time, has told the Commission on Wartime Relocation and Evacuation of Civilians. "We couldn't make the nice distinction," he said, "that perhaps you could in peacetime."

The federal commission, which is considering payment of reparations to those interned during World War II and their heirs, has gathered documents showing:

* The FBI, Naval Intelligence and President Roosevelt's personal intelligence operative all agreed that internment of Japanese Americans was unnecessary. "The necessity for mass evacuation is based primarily upon public and political pressure rather than on factual data," FBI Director J. Edgar Hoover reported at the time.

* Once internment went ahead anyway, top officials conceded that even if it was necessary at the beginning of the war, its justification evaporated within a year or two. But internment continued through December, 1944, for largely political reasons. Notes from a May, 1944, Roosevelt Cabinet meeting report that, "The secretary of war raised the question of whether it was appropriate for the War Department, at this time, to cancel the Japanese exclusion orders and let the Japs go home. War, Interior and Justice had all agreed that this could be done without danger to defense considerations, but doubted the wisdom of doing it at this time before the election . . . ."

* Unconcealed racism infected the thinking of the military officer chiefly responsible for the evacuation decisions, General John L. DeWitt. "In the war in which we are now engaged racial affinities are not severed by migration," he said in one memo. "The Japanese race is an enemy race and while many second- and third-generation Japanese born on United States soil, possessed of United States citizenship, have become Americanized, the racial strains are undiluted."

* The press, with few exceptions, fueled the hysteria. "I know this is the melting pot of the world and all men are created equal and there must be no such thing as race or creed hatred, but do those things go when a country is fighting for its life?" Hearst columnist Henry McLemore asked rhetorically in a Jan. 29, 1941, column. "Not in my book," he declared. "No country has ever won a war because of courtesy and I trust and pray we won't be the first . . . . I am for immediate removal of every Japanese on the West Coast to a point deep in the interior. I don't mean a nice part of the interior either. Herd 'em up, pack 'em off and give 'em the inside room in the badlands. Let 'em be pinched, hurt, hungry and dead up against it . . . . Personally, I hate the Japanese. And that goes for all of them."

Elected leaders, including Earl Warren, who later became chief justice of the United States, incited the press and public. ". . . It is certainly evident that the Japanese population of California is, as a whole, ideally situated, with reference to points of strategic importance, to carry into execution a tremendous program of sabotage on a mass scale should any considerable number of them be inclined to do so," Warren, then California attorney general, said in February, 1942, as the government ordered the internment of Japanese Americans.

President Roosevelt approved the internment. But he devoted little attention to it. "I don't really think he spent much time on it," Edward J. Ennis, a Justice Department official at the time, told the commission. "It was . . . it's a terrible thing to say, but it was a minor problem with the president."

Historically, the wartime internment decisions stemmed from decades of open racial antagonism and discrimination against Japanese immigrants to the United States, as shown by these headlines from the San Francisco Chronicle in 1905: Brown Men an Evil In the Public Schools Japanese a Menace To American Women Unclean Practices of Orient Bringing Degradation and Debasement in the Train Of Unrestricted Immigration Whole State Stirred by Menace Of the Invasion

Rather than subsiding as the immigrants established themselves and achieved success in farming and running small businesses, racial antagonism intensified. Discrimination against Japanese Americans became official policy in segregated schools, local laws forbidding land ownership, and, nationally, by legislation barring "Orientals" from U.S. citizenship.

When World War II broke out, these laws made thousands of Japanese Americans "enemy aliens," subject to arrest and detention without charge. Even before Pearl Harbor, the FBI and the Justice Department had made them targets of an elaborate system of surveillance and classification on lists.

If considered "dangerous" because of association with Japanese institutions such as the Buddhist Church, the government classified them "A", James Rowe Jr., then assistant attorney general told the Wartime Relocation Commission. "If the evidence was good, they would be marked with an 'A-1.' If poor, A-4.' It was pretty thin stuff."

Nevertheless, the lists were used for arrests of 2,192 aliens between the attack on Pearl Harbor and the middle of February, 1942.

Amidst headlines about Japanese victories in the Pacific, the press reported the roundup of Japanese Americans as part of the war effort. The Washington Post reported on its front page on Feb. 6, 1942: FBI Seizes 15 in Mare Island Spy Roundup

"FBI agents, acting to nip fifth-column activity around the huge Mare Island Navy Yard, raided Japanese and Italian alien-owned establishments in Vallejo today."

The raids and the publicity contributed to suspicions of subversion. They helped prompt vigilante attacks on people of Japanese ancestry, as well as on Chinese mistaken for Japanese. Life Magazine, on Dec. 22, 1941, offered guidance in an illustrated article entitled: "How to Tell Japs From the Chinese."

Some Italian and German "enemy aliens" also were detained, but a secret study circulated in the War Department concluded that "the great bulk" of the German and Italian aliens "are believed to be thoroughly loyal to the United States."

But Gen. DeWitt, U.S. commanding officer on the West Coast, told Assistant Secretary of War McCloy over the phone early on Feb. 3, 1942, "If they the Japanese Americans are allowed to remain where they are, we are just going to have one complication after another because you just can't tell one Jap from another. They all look the same. Give a sentry or an officer or troops any job like that, a Jap's a Jap, and you can't blame the men for stopping all of them.

". . . About the Germans and the Italians, you don't have to worry about them as a group. You have to worry about them purely as certain individuals. Out here, Mr. Secretary, a Jap is a Jap to these people now."

At hearings then to assess the West Coast threat, California Attorney General Warren testified that while many "are of the opinion that because we have had no sabotage and no fifth-column activities in this state . . . that means that none have been planned for us . . . . I believe that we are just being lulled into a false sense of security and that the only reason we haven't had disaster in California is because it has been timed for a different date."

A March 5, 1942, cable from a government agent on the West Coast warned Washington: "It cannot be too strongly emphasized that the public want the Japanese evacuated immediately . . . . P.M. issue of March 5 San Francisco Examiner carried four-inch banner headlines stating Honolulu bombed by mystery plane. San Francisco Chronicle is working on the story . . . . Newspapers are carrying many stories concerning the Jap infiltration of ownership of land surrounding vital areas, including major highways, power lines, aircraft factories, oil refineries and railways . . . some feel it is better to send a thousand innocent people away than risk sabotage by one."

During testimony before the Wartime Relocation Commission, Boris T. Pash, who was a government counterintelligence officer on the West Coast during the war, was asked by former U.S. senator Edward W. Brooke, a commission member, "if, at any time, you had information that any Japanese Americans were involved in espionage or sabotage?"

"Well, the thing is that it was difficult," Pash answered. "We had no information except, at that time, for example, a preliminary warning of a submarine attack. That attack took place by the way an hour or so after the warning came."

Brooke: Warning came from what source?

Pash: An anonymous phone call.

Brooke: And, did you presume that to be a Japanese American?

Pash: No, we didn't presume. The person calling said he was a West Coast Japanese.

But conflicting intelligence estimates came from presumably more reliable sources. In November, 1941, a month before Pearl Harbor, Curtis B. Munson, a Chicago businessman who doubled as an intelligence adviser for the president, reported to Roosevelt that "for the most part, the local Japanese are loyal to the United States or, at worst, hope that by remaining quiet they can avoid concentration camps or irresponsible mobs. We do not believe that they would be at least any more disloyal than any other racial group in the United States with whom we went to war."

On Jan. 29, 1942, Lt. Cmdr. K.D. Ringle of Naval Intelligence said in a report that "the entire 'Japanese problem' has been magnified out of its true proportion, largely because of the physical characteristics of the people . . . . It is no more serious than the problems of the German, Italian and Communistic portions of the United States population and . . . should be handled on the basis of the individual, regardless of citizenship, and not on a racial basis."

The FBI also consistently downplayed the threat, based on reports from its agents in Hawaii and on the West Coast. Hoover felt his bureau had basically dealt with the problem in arresting "enemy aliens" and could continue to handle it that way.

After Lippmann's commentary about the "fifth-column" problem, Attorney General Francis Biddle told President Roosevelt: "Either Lippmann has information which the War Department and the FBI apparently do not have, or he is acting with dangerous irresponsibility."

To help the government track Japanese Americans, the Census Bureau departed from its policy of confidentiality in 1941, after the 1940 census, to produce a duplicate set of cards and cross-tabulations of where they lived, down to the city block, Census Bureau official Calvert Dedrick told the Wartime Relocation Commission.

Dedrick said the bureau discovered a "very interesting sociological human phenomenon" as it gathered information to help the military prepare for internment. Japanese Americans who had been widely scattered in rural areas appeared to be migrating to denser urban concentrations. The Japanese Americans, he concluded, were massing together in fear. NEXT: Virtual martial law

Staff researcher Carin Pratt contributed to this series. graphics 1/photo: By Russell Lee, courtesy of the Library of Congress Gathered and guarded at railway station in Los Angeles, West Coast Japanese Americans in April, 1942, wait under war orders for transportation to internment camps.