A group of about two-dozen U.S. Marines, some of them apparently drunk, invaded a Capitol Hill bar for homosexuals early yesterday, assaulted one of the bar's owners, broke windows and damaged a liquor store next door, police reported.

The group was among 150 persons, most of them Marines, who had gathered around midnight in a small park across from the Equus bar at 639 Pennsylvania Ave. SE, brandishing sticks and shouting antihomosexual slogans. According to bar owner Dennis Graham, they jostled a D.C. police officer trying to disperse the crowd in the park before the alleged assault on his partner.

Police said that two Marines were arrsted for disorderly conduct, fined $10 each and turned over to military authorities.

Other than the bar owner, who was treated at Capitol Hill Hospital and released, there were no serious injuries reported.

D.C. Police Sgt. J. Simmons, the first officer on the scene at Sixth Street and Pennsylvania Avenue S.E. ordered the crowd to disperse. Instead he was grabbed by several of the men who hoisted him above their heads and began reaching for his gun. They dropped him and ran as other police arrived on the scene, Simmons said.

"This one was bad. We have had several incidents with a few Marines in the past. But nothing like this," a shaken Simmons said at police headquarters yesterday.

The incident is the sixth confrontation between Marines from the 800 person barracks at Eighth and I Streets SE and the patrons and owners of the Equus since the bar opened last April, Graham said.

It was by far the largest such disturbance, according to Graham. "I'm at the point where I've been pushed too far," said Graham, as workmen arrived to put in new glass. "I've talked to all the gay organizations in the city and something is going to be done."

These Marines have committed crimes," said longtime gay activist and D. C. Human Rights Commissioner Franklin Kameny. "I would like to see every Marine involved in this court-martialed. If they don't do that, they are not meeting their responsibility.

According to Marine Capt. J. M. Paxton, Marine Corps officials have had no reports of such an incident taking place, although he admitted that two Marines were arrested and turned over to the Shore Patrol.

According to some Marines, the incident may have been a reprisal for alleged attacks by homosexuals on Marines in the area as well as the result of other frictions between the Marines and the Capitol Hill community.

"Some of these guys from different parts of the country can't tolerate people who are different," said one Marine, who asked not to be named.

The incident began about midnight when the large group of crewcut Marines along with several women and longer-haired men entered Eighth Street and marched north toward Pennsylvania Avenue, one witness said.

Harry Carr said he was drawn from the basement of his home near Sixth Street and South Carolina Avenue by the sound of chanting. He followed the marchers to the corner of Sixth Steet and Pennsylvania Avenue, but stopped when he saw the size of the crowd and the police cars coming, Carr said. Several of those in the crowd threatened him, he said, and he was upset by the attitude of the police.

"I thought they were going to detain them. Windows were broken and trash was all over the street. But they just herded them back toward the barracks; they didn't even get out of their cars," Carr said.

When he asked one police officer what they were doing about the Marines, Carr said he was told, "Oh they're just out having a good time. I used to be a Marine myself. You just go on home."

Don King, owner of the Penn Theater across the street from the bar, was dining at Las Asturianas Restaurant on Eighth Street SE when, he said, he heard a "strange chanting" shatter the quiet of the empty street.

It was walll-to-wall Marines from sidewalk to sidewalk," he said. "A few of them were brandishing sticks. I've never seen anything like it."

"At first, King said, he feared it might have been some sort of racial uprising because the crown was predominantlyl white. King often employs Marines from the barracks in his theater and was surprised at the incident.

"I never would have expected it. It was not a spur of the moment thing. The thing that puzzled me, is how do you get something like that together so fast?" he said.

The 75 to 80 patrons at the Equus ran out the back door when the Marines entered, according to Rick Holloway, the co-owner of the bar, who was assaulted.

"It happened so fast," said Graham. "My partner was standing at the end of the bar, heard windows breaking, turned around, and was decked."

"I'm sure there will be a retaliation, if we can arrange it," said Holloway, still suffering blurred vision from the assault. He added, however, "Gays in this city are not a violent people. They don't display themselves as anything but what they are."

One Marine who said he was not involved in the incident, said he feared the possibility of retaliatory attacks on persons in Marine uniforms as well as probable disciplinary action by the barracks commandant.

"I don't think it's fair that everyone is gonna be punished for a bunch of guys who get a stomach full," he said.