There is little sign of the carnage that took place here. The then-barren sides of Mount Suribachi, the extinct volcano where six marines raising the American flag were photographed in the most vivid image of the island war in the Pacific, now are covered with vegetation.

Forty years ago today, U.S. Marines assaulted a two-mile-long beach of gray volcanic ash on this island to begin a climactic battle of World War II. When it was over, 36 days later, 6,800 Americans and more than 20,000 Japanese lay dead.

To mark the anniversary, about 270 American and 110 Japanese veterans and family members gathered -- jointly for the first time -- on a gently sloping hillside above the invasion beach and dedicated a stone memorial praising the "bravery and honor" displayed on both sides.

As the anniversaries of the war's events accumulate, this one stands in contrast to ceremonies last June marking the 1944 invasion of Normandy, at which West Germany did not play a role.

"Suribachi smiles today for the souls of Iwo Jima, freed at last by peace and brotherhood," W.J. Ridlon, Jr., a retired Marine colonel who fought at Iwo Jima, told the gathering. A message from President Reagan said, "You have given us a special meaning for the word 'courage.' "

At the White House, Reagan received 325 "men of Iwo" and family members, The Associated Press reported. The veterans sang "The Marine Hymn."

Aging marines came to attention and a few wiped away tears as a bugler sounded taps. After a Shinto priest performed rituals honoring the dead, the Japanese sang the hymn of the Association of Iwo Jima, which links Japanese survivors and relatives of the battle's victims.

Miyano Katsumori, a Japanese woman whose brother died at the foot of Suribachi, said after the ceremony: "I think that under the ground, he is very happy."

As the survivors strolled the beach, they were asked to be alert for the bones of the dead.

They are still found here, mummified inside the maze of tunnels and caves that enabled the Japanese to delay victory by the assaulting Americans. In the past three weeks alone, 75 sets of remains have turned up.

Today's ceremony was a moving act of reconciliation between soldiers whose hatred for each other was perhaps stronger than in the European theater of the war. Here, combatants on both sides often took no prisoners.

"For me, it's over," said Norman Baker, a Fauquier County resident. "I came here to see a peaceful island."

But here and there were signs of lingering bitterness. Some Americans stood back as comrades shook hands with the Japanese. And some Japanese said the United States was not helping in the search for Iwo Jima dead.

After the ceremony, things assumed a more festive air. The Americans walked the beaches, pocketing shrapnel from the sand, explored old blockhouses and gawked in amazement at the view from atop 560-foot Suribachi, from which the Japanese had lobbed shells onto the beach below.

Yoshio Komatsu, who was one of the mountain's gunners, met Wayne Bellamy, of Phoenix, Ariz. "I was among the first troops that landed at the base of Suribachi," Bellamy told him. "Yesterday's enemy, today's friend," smiled Komatsu.

Iwo Jima 40 years later is a symbol of the military cooperation that Japan and the United States began after the war. The island, five miles long, accommodates a U.S. Coast Guard navigation station and a base for Japanese planes that help U.S. aircraft patrol Pacific sea lanes. There are no civilian residents on what are actually three islands. The United States returned them to Japan in 1968.

Located 650 miles south of Tokyo, the main island was viewed by U.S. military planners late in 1944 as crucial for strategic bombing of the Japanese mainland that was getting underway. Seizing Iwo Jima would deny the Japanese a base from which their fighters were attacking U.S. B29s.

On Feb. 16, 1945, U.S. warships arrived off Iwo Jima (meaning "Sulfur Island") and began a sustained barrage. On Feb. 19, marines climbed into amphibious tractors and headed for shore. An eventual 75,000 Americans were to meet about 22,000 Japanese.

The Japanese had been preparing for years. About 640 pillboxes and blockhouses had been built on the island, which is only about a third the size of Manhattan. The commander, Lt. Gen. Tadamichi Kuribayashi, ordered his troops to let the Americans reach shore and then to open up from hidden positions.

The Marines were supposed to capture Suribachi the first day. With artillery, mortars, rockets and small-arms fire raining down, four days passed before the summit was in U.S. hands. But "we didn't realize when the flag went up that the worst was yet to come," said Robert Owensby, from Naperville, Ill.

For the next four weeks, the marines fought a murderous battle yard by yard across the barren island, using flame throwers, explosive charges, and bulldozers against Japanese holed up in a vast network of steamy caves, tunnels and blockhouses. Slowly the Americans advanced northeastward, fending off suicide attacks at night.

Gradually, organized resistance collapsed. Kuribayashi, after organizing a final attack from his headquarters at the north end, committed ritual suicide on March 27. Stragglers continued to hide -- a few somehow held out until 1951.

Today's events were initiated by veterans' associations of the 3rd, 4th and 5th Marine Divisions. With the help of the U.S. Embassy in Tokyo and the Japanese Foreign Ministry, they organized the first formal reunion on the island involving soldiers from the two sides.

The Americans returned today aboard U.S. C130 transports flying from Japan and were amazed to see their island grown over by foliage seeded by U.S. airplanes after the war. Many of the caves and gullies so deeply rooted in their minds were no longer recognizable.

Now in their late 50s or early 60s, the Americans joked about their waistlines and tendency to ramble on about the Japanese. "We killed almost a million of them coming here on the plane from Los Angeles," said veteran Claude Duval. Many had to correct themselves after using the term "Jap," which tour organizers tried to ban.

For most, the eight hours on Iwo Jima was a moving experience. During the battle, "I felt that God was right there, standing right next to me," said former marine officer John Sbordone, who returned wearing his old fatigue jacket and carrying his field map.

Some, like Richard Smith, a former artillery spotter, said that he had no desire to fraternize with the Japanese veterans. "I'm one of those unreconstructed guys who thinks we should have flattened Tokyo with an A-bomb," he said.

Other Americans sought out the former enemies. One returned a diary he had taken as a war trophy. Another returned a flag. After the ceremony, there was much shaking of hands and posing for joint pictures, and a few embraces.

Joseph Selby of Maple Shade, N.J., passed around photos developed from film in a Japanese camera he had captured. One showed two Japanese soldiers posing against a rock wall. Masahiro Kawai, son of a man who died on the island, told him, "I think this is my father." Selby gave him the photo and the two men exchanged addresses.

Japan lost 3 million in the war and Iwo Jima is viewed as another in a long line of debacles leading to Hiroshima. Many young people today do not know the island's name.

Shiro Ishiwata, a former sergeant who commanded a field gun, said he came partly to revive memories. "Forty years after the battle, I scarcely remember whether I was at Iwo Jima or not, unless I see the wound on my arm," he said. He said it was also necessary to build friendship with the Americans: "Peace will not be realized just by saying the word."

Iwao Matsumoto, a former Imperial Navy petty officer in intelligence, said he was coming partly to apologize to the spirit of Gen. Kuribayashi, who had ordered him and others somehow to flee the island and report to Tokyo. Matsumoto ended up a wounded POW. "I want to report to the general that I could not accomplish his order and that I am sorry for that," he said.