Even today, 40 years later, many people who were in Tokyo the night of March 9, 1945, and survived cannot look at the colors of a sunset without remembering.

The skies glowed a ghastly scarlet much of that night, as wave upon wave of American B29 bombers dumped napalm cylinders onto the largely wooden city and set off one of the worst firestorms in history.

In a few hours, 16 square miles of tightly packed homes and factories were destroyed. Close to 100,000 people died. Millions of Japanese came to know that the war could seek them out even in their homes.

The great Tokyo air raid, as its survivors call it, killed almost as many people as did the atomic bomb at Hiroshima five months later. It killed many more than the Nagasaki bomb. While official estimates of the number who died in the air raid and firestorm range from 72,000 to 89,000, survivors' groups maintain that the number of dead was actually much higher.

But today, with all signs of the carnage wiped away by Tokyo's postwar prosperity, many of those who lived through it worry that it will be forgotten.

This weekend they are gathering to tell their stories and try to keep memories alive. A march of commemoration is also being held.

They are also working to collect a million signatures to press the Tokyo city government to build a special museum or archives to document the raid.

"We must convey this sadness to the next generation and make all efforts to see that it does not happen again," said Yoshiko Hashimoto, who as a young woman lost her mother to the flames and became an antiwar activist.

As in America, the war is a crucial barrier between generations here. Forty years later, people who lived through it often feel that it forced on them a special wisdom and strength younger people will never understand.

The March 9 attack signaled a shift in strategy for the U.S. air campaign against Japan. According to author John Toland, it was ordered by campaign commander Gen. Curtis E. LeMay without consultation with Washington.

American bombers had been hitting Japan steadily since 1944, generally using large, high-explosive bombs. But LeMay concluded that these methods were ineffective against Japan's widely dispersed industrial base and decided to use fire.

So, on March 9, bombers loaded with two-foot-long napalm cylinders took off from Guam, Saipan and Tinian islands. More than 330 of the planes formed a giant air armada and headed north for Tokyo.

The city was largely undefended and its 4 million people unprepared for what was coming.

The government had cut fire lanes through its more crowded neighborhoods and evacuated large numbers of children and old people to the countryside.

But leaders felt that Tokyo's best protection was in keeping most of its people at home. With water, sticks with wet rags on the end and padded fire capes, they would turn out en masse to defend their houses and keep any fire from spreading far.

As the first planes approached the city around midnight, air raid sirens wailed. But for some reason, authorities concluded it was a false alarm and sounded the all-clear. People breathed easier.

Kiyo Miyashita remembers hearing the second siren and thinking it was safe to go to bed. But, suddenly, bombs began falling, and fires erupted nearby.

"The window on the south side of the house turned totally red," she recalled.

The B29s concentrated on the "low city" area of western Tokyo, a teeming hive of working-class homes and small factories. They scattered the napalm bombs -- by some counts, as many as 700,000 were dropped that night -- from altitudes so low that people felt they could bang on the planes' wings with a clothesline pole.

Koyo Ishikawa, a Tokyo policeman charged with photographing air raids, was on duty at police headquarters when the raid began. Suddenly, he remembers, 60 or 70 telephones began ringing in unison. Breathless officers in the "low city" stations conveyed news of a mammoth raid.

Ishikawa jumped into a car with his Leica camera and hurried toward the low city. He left the vehicle at a bridge and fought his way through a mob of refugees to reach a police station.

Ishikawa quickly realized he had made a mistake. The fire, now generating powerful winds that whipped up a storm of ashes and dust, was closing in on the station. Everyone fled.

He survived the night because in the ruins of a house he saw a sunken bathtub, with water dribbling from a broken pipe. He lay down in the tub, soaked himself in the water and stayed put.

"All night I could hear the sound of houses burning, houses collapsing, B29s overhead and firebombs exploding," he said. At times the smoke cleared and he could see more bombers coming, their silver bodies reflecting a dull red from the flames below.

At one point he peered from the tub and saw a woman trying to run to safety from some type of flimsy shelter.

"All of her clothes suddenly caught fire at once. The wind blew her down and she rolled, burning and screaming," he said.

Miyashita had better luck. She, her husband and mother-in-law grabbed ration cards, rice, a Buddha image and other belongings and hurried out onto the streets, which were already jammed with panicky people.

They made their way for two miles through flaming and smoky neighborhoods, discarding many of their things along the way. They took refuge at a bridge over the Nakagawa stream and waited.

All that night, life or death was determined by chance, by whether people were at home or at work when the planes came, whether they turned left or right when they tried to flee.

As the heat soared, bundled babies carried on their mothers' backs caught fire. Whole families died as their burning houses collapsed into shelters dug under the floors.

Swarms of people found refuge on the banks of the Sumida River, only to be pushed into the water by the press of newcomers and drown.

Other crowds flocked to the grounds of the renowned Asakusa shrine, in the hope that it would somehow be immune to the flames. But fire closed in there too, burning large numbers of people.

Hashimoto last saw her mother on a bridge spanning a small canal that they had reached.

"She took off her air raid hat and gave it to me and told me, 'Jump into the water with your baby.' The wind fanned out her hair."

Hashimoto passed the night clinging to a raft in the canal. She and her son lived even though the heat was so intense that the ropes holding the raft together caught fire.

Singed and exhausted, photographer Ishikawa emerged from his tub at about 4 a.m., convinced he was the only person who had survived. But in the distance, through smoke and haze, he could see clusters of people on their feet.

"Someone else had lived," he recalled. "It was the happiest feeling of my life. We embraced and congratulated one another for being alive."

Outraged at the carnage the United States had created, Ishikawa began taking pictures. He deliberately chose the grisliest sights he could find -- a canal choked with bodies, dead mothers and their children -- to create a full record of what had been done.

He looked for his car. All that was left was its chassis. He walked back to police headquarters.

That same morning, Miyashita returned to her neighborhood to find blackened corpses strewn about and destruction so total that she had trouble finding her house. All that she could make out was the metal legs of her sewing machine.

All three people living there had survived. But her father, sister and brother, living nearby, had vanished. Their house was ashes and their bodies were never found.

Tokyo's newspapers did not report the extent of the death and damage. But the entire city knew something horrible had happened. Many concluded that the war must be going badly for Japan.

Others, however, seemed to see it as an act of God, a natural catastrophe akin to the earthquake that had leveled the city 22 years earlier.

"Even after everything burned, I never thought that Japan would lose the war," said Miyashita.

The American public, little aware of the horror on the ground and hoping for a quick end to the war, welcomed the raids. Time magazine observed that "properly kindled, Japanese cities will burn like autumn leaves."

In following days, mass graves were scooped out in Tokyo's parks and bodies were quickly buried. Tens of thousands were never identified. There were many more raids before the surrender Aug. 15, but never one as terrifying as the March 9 raid.

The U.S. occupation authorities discouraged remembrance of the raid, survivors said. They said that attitude was inherited by the Japanese government.

But in the 1970s, survivors began working on their own to chronicle the raid. Novelist Katsumoto Saotome, who as a 12-year-old boy was grazed on the shoulder by a falling firebomb while fleeing the raid, organized a team of researchers. They interviewed more than 1,000 survivors, visited the U.S. National Archives and eventually published a five-volume history of the Tokyo raids.

This spring, the newspaper Asahi Shimbun has sponsored an emotionally powerful exhibit documenting the raids. On display are the pathetic air raid capes and a few of the napalm tubes.

The purpose is promotion of peace, not anti-Americanism, organizers say.

"It is important not to forget what Japan did to other countries," said Saotome. "That is why we decided to include pictures of Japan's air raids on China."

The low city today is completely rebuilt. Here and there, tiny Buddhist images mark the sites of particular deaths. But no ruins have been preserved as a memorial.

People who want to pay respects to the victims come to an imposing shrine with a Japanese-style tile roof, built originally to house the ashes of victims of the 1923 earthquake.

There, the ashes of 60,000 people killed the night of March 9 are kept in a great common bin.

At first appearance, the shrine seems to be made of wood. But it is concrete. It and the ashes inside will be safe from any future conflagration.