The Department of Defense, responding to the frustrations of military families who had suffered through four days of agonizing uncertainty, early today began releasing the names--unit by unit--of the 1,400 Marines stationed in Lebanon who were unharmed by Sunday's terrorist bombing at the Beirut airport.

The unprecedented listing of survivors created a situation in which a family might conclude through a process of elimination that a loved one is dead.

Pentagon officials decided the action was necessary, however, because survivors were having such a difficult time calling home to report their safety to their families. Another factor, officials said, was that it might take several more days, and perhaps weeks, before the remains of all victims of the Beirut bombing are identified.

Release of about 100 names was made to the media last night, but Pentagon officials then said the list contained inaccuracies and asked that it not be made public. It was released again about 1 a.m.

"It will be slow, very slow. It is just not something we can do quickly," a U.S. Marine Corps spokesman said at the Pentagon. He said most of the dead servicemen were not wearing their "dog tag" identifications when they were killed, and many bodies were so mangled and charred that identifying them is exceedingly difficult.

Most dental and medical records of the victims apparently were destroyed in the blast, although search teams announced yesterday that they had found some personnel documents that might speed up the identification process.

Pentagon sources said last night that, in addition to releasing the names of the survivors, they also were considering notifying the relatives of unaccounted for Marines that those servicemen were missing, rather than waiting for positive identification and reporting them dead.

As of last night, the Defense Department had released the names of less than half of the servicemen listed as killed or missing in the bombing. The estimated death toll stood at 219. The decision to begin releasing the names of survivors came in the face of intense pressure from members of Congress to do something to ease the agony of military families who had heard nothing for four long and sleepless days. As the hours dragged painfully on with so little news, more and more congressmen were getting calls from anguished families pleading for help.

Sen. Edward M. Kennedy (D-Mass.) wrote a letter to Marine Corps officials here urging them to release the names of survivors as "a humane act" after his staff had received several calls from frustrated families. Kennedy's press secretary, Robert Shrum, said he received one call from a father who said, "Please help me. If you can't help, at least pray for me."

The Marine Corps' congressional liaison office responded to Kennedy's letter yesterday morning, informing his office that the Marines would begin compiling lists of survivors in Beirut and release them as soon as possible.

The difficulty even congressmen were having in assisting anguished families was characterized by a case handled by Rep. Carroll Hubbard Jr. (D-Ky.).

Last Sunday, hours after the bombing of the Marine quarters in Beirut, Hubbard's office received a call from Charles A. Norfleet Sr. of Pembroke, Ky., reporting that his son was with the Marines in Lebanon and he was anxious to learn of his condition. Hubbard's administrative assistant, Jim Knouse, who served as an Army officer for 20 years, immediately began calling all of his military contacts.

On Sunday he heard nothing. On Monday he could get no information on Norfleet's son. Again Tuesday he could learn nothing. In exasperation, Hubbard took the House floor yesterday to criticize the slow flow of information. Finally, at the very hour Hubbard was speaking, Knouse learned that Charles A. Norfleet Jr. was alive and unharmed.

"That family went through 81 hours of agony and other families are suffering even more," Hubbard said. "Surely there must have been a better way in this computer age for the strongest military force in the world to inform the next of kin about their Marines."

For hundreds of military families around the country, however, the hours of waiting had not ended. And in several cases their agony had only been compounded by gruesome mistakes and hoaxes.

Leile Roque of Springfield, Mass., said she was awakened at 3 a.m. yesterday by a man identifying himself as a Marine lieutenant. He reported that her son was injured in Beirut. Later, however, she called the Marine hotline and learned that her son's condition was still unknown.

In Richmond, the father of Navy Petty Officer 3rd Class William B. Foster Jr. was told that his son had been injured and was recuperating in a hospital in West Germany. His parents were relieved that the news was not worse, until they learned that it was false.

"They got the names mixed up, and it was a John Foster instead of W.B. Foster," said the father, William B. Foster Sr. "It was a computer error or something like that. They said they didn't know anything about my son . . . . I'm worse off now than I was before. I don't know anything now."

In West Germany, meanwhile, forensic teams were still working to identify many of the bodies, doctors were treating the wounded, and officials were preparing to ship some of those not seriously injured back to the United States, perhaps as soon as today or Friday. Reporters yesterday were allowed to speak with three of the injured Marines, who were clad in blue robes and sitting in wheelchairs.

Burham Matthews of Odenton, Md., said he was awake and already in uniform when the blast leveled their headquarters building in Beirut. He said he was standing next to a good friend "when I heard a couple of gunshots and someone yelled, 'Get down!' and I heard the truck smash into the guard shack and the bomb went off.

"I didn't really realize what was happening. I got blown out the window but I was fully conscious. I tumbled through the air and I remember things flying past me. I landed on my feet and watched the roof of the building hit the ground."

Matthews said he heard one of his best buddies "screaming for me. He was crying out my nickname 'Animal' and I went to try to find him but he was buried too deep. I couldn't find him."

That buddy is most likely among the bodies in the Frankfurt morgue that soon will be transported by cargo planes to the Dover Air Force Base in Delaware. A hangar there has been transformed into a chapel where a memorial service will be held when the bodies arrive.

At Camp Lejeune, N.C., the home base for most of the Marines killed and injured in Beirut, preparations were under way yesterday for the arrival of some of the wounded. Maj. Gen. A.M. Gray, commander of the 2nd Marine Division there, said the first group is expected to arrive this afternoon. A base chaplain said he has received hundreds of offers of housing for out-of-town relatives expected to congregate near the base when the men start coming home.

In small towns and cities across America, 40 more families yesterday received the news that their servicemen were dead or missing. One of those was the family of Lance Cpl. Rick Crudale, who was pictured holding a machine gun earlier this month on the cover of Time magazine. When asked how Crudale's wife, Heidi, was holding up, his mother, Marie, said, "Not very well."

Along with the personal grief borne by the families of the dead and wounded fighting men, the events of the last four days--first the bombing in Beirut, then the U.S. invasion of Grenada--stirred deep emotions throughout the country.

Some 5,000 protesters, holding hands and chanting, marched from the United Nations to Times Square in New York last night, making known their opposition to the U.S. invasion of Grenada. More than 2,000 people marched through the streets of Berkeley, Calif., chanting, "U.S. out of Grenada now." Hundreds of other protesters gathered in front of federal buildings in San Francisco, Detroit and Boston and on college campuses to challenge the invasion of the small eastern Caribbean island.

Marine recruiters, meanwhile, reported that they were being flooded with requests from young men, flushed with newly stirred patriotism, who wanted to join the corps or reenlist. "Just today I've had 30 to 40 phone calls from former Marines wanting to reenlist," said Lt. Col. James Bathurst, commander of Marine recruiting in northern Illinois and Indiana. "On a normal day, I might get one."

In New York, three dozen Marines and hundreds of people attended a special mass at St. Patrick's Cathedral. The Rev. James Rigney told the worshipers not to blame God for the tragedy. "When something terrible happens, we may be inclined to say, 'Why did God do this?' We know that God did not do it. People did it to other people."