HARVARD SQUARE was a contused chessboard this summer; at times the conflict was open, bricks and sticks meeting clubs and tear gas. But more often the conflict was below the surface, a confused struggle which no one understood. The signs of victory and defeat were subtle; the number of policemen in the Square, of boards on shop windows, of panhandlers in Forbes Plaza and newspaper hawkers on the MBTA traffic island, of signs and posters on the boards covering the front of the Cambridge Trust Co., served as an indicator of the flux of forces controlling the Square on each particular day.

The first indication of the coming battle was the influx of "street people" at the beginning of the summer. Like the runaways who came to Boston two years ago, they had heard that Cambridge was where the dope and music were, and they came to cash in. Some estimated the average daily floater population of Cambridge as above 4,000. People working at Project Place estimated by the end of the summer that one out of six street freaks sitting at Forbes Plaza was on heroin.

The influx intensified the uneasy cultural interface in the Square. Panhandlers and Panthers abounded in front of Holyoke Center and on the MBTA island, and, according to Cambridge merchants, the suburban shoppers with the really big money began finding other places to do their shopping.

But, even so, it looked at first as if the City was bending over backwards to be fair, if not friendly. There were, of course, the Sunday afternoon concerts on the Common. And there was also Summerthing's Schaefer Beer Music Festival in Harvard Stadium.

For the first concert, the organizers had gotten a pledge from the police that they would not come into the Stadium unless requested to do so. On June 23, when the Band came to Cambridge to play on the futuristic sound stage erected in the south end zone, the only security forces in the Stadium were hired guards wearing red T-shirts stenciled with peace symbols. At two dollars a throw and no reserved seats, the concerts were not exorbitant; but a lot of people got in free anyway. Half an hour before the concerts began the red ropes indicating authorized seating had lost all meaning as freaks swarmed past them.

The concert itself was euphoric: the Band was in perfect form, and as the evening progressed the crowd surged down into the area in front of the stage, jamming it tight in a mass of wriggling, dancing ecstatic human flesh. The Band played for more than an hour, and at the end of the concert one of them told the crowd, "We're going to tell all our friends in Woodstock that Boston is one of the best places in the world to play music."

BUT if all was good vibes at the Band concert, the Ray Charles show the following Wednesday set the tone for something closer to what the summer would become. Charles' set-piece, big-band presentation did not capture the crowd like the Band's dancing rock. Scuffles broke out in the crowd around the stage as the Ray Charles Orchestra warmed up, escalating into a full-scale fight shortly after Charles came on stage. The blind singer, unaware of the brawl taking place only feet from his piano, continued playing while the crowd, ignoring the music, watched the combatants surging in the pit.

When the fight had been broken up, the concert began again; but the mood was gone, and shortly after the Raelettes had come on stage, a quarrelsome drunk began to heckle Charles from the front of the pit. Visibly annoyed at last, Charles stopped and let the drunk talk while the crowd grew angrier and angrier. Someone in the back yelled "shut up, asshole!", the noise subsided long enough for a brief set, and Charles left hurriedly.

After the concert, the tensions which had smoldered inside the Stadium broke out anew. Gangs of black and white high school students began fighting as the crowd walked up Boylston St., and small groups of teenagers ran along the edges of the crowd, grabbing purses and leaving several women with bloody noses. As the crowd reached the Square, the newsstands closed abruptly, and the purse-snatching and fighting continued around the Square for about twenty minutes until police arrived.

The next day the Record-American and the Herald-Traveler ran big stories headlined "200 Youths Rampage through Harvard Square," and the temperature around the Square began to go up.

But it took a month before the pot began to boil. On Thursday, July 23, leaflets began circulating around the Square urging people to celebrate the anniversary of Fidel Castro's July 25 attack on the Moncada Barracks by holding a "block party" on the Common that Saturday night. Although it did not say so explicitly, the leaflet clearly implied that those who came should be prepared to celebrate violently.

The leaflet became an object of heated debate on Saturday and Sunday. Bread and Roses circulated a counter-leaflet warning that the original leaflet bore the mark of a provocateur: it was male chauvinist, addressing its readers as "Brothers"; it also said "you have to fight," not " we have to fight" as a real movement group would have. In addition, it was unsigned, and contained a rather condescending invitation to Panthers to join in the block party.

Despite the discouragement from Bread and Roses and other radical groups, more than 200 young people-assembled on the Common that Saturday night, milled around confusedly, shouted slogans, and burned an American flag. The group then moved into Square, throwing rocks through windows and looting.

Police from Cambridge, Boston, and the Metropolitan District Commission moved in with nightsticks and tear gas. When the evening was over, five people had been arrested on charges of receiving stolen property, disturbing the peace, and assault and battery. Seven, including two policemen, were treated for injuries.

At this point, the merchants in the Square area, hit by the third sizeable riot since May, began to coalesce into a powerful group in the conflict over the Square. Citing losses of over $50,000 in the latest outbreak alone, they held a meeting the following Monday and decided to ask the City Council for fast action. Since they represented the largest commercial area in the City, they got it.

That night the Council passed a 9 p. m. to 8 a. m. curfew for the Common-intended to cover only groups loitering there, not persons walking across. Shortly afterward the Council asked the Summerthing to cancel its remaining concerts and requested that Harvard take steps to prevent "disreputable persons" from congregating in the area of Forbes Plaza. The Council also ordered the Cambridge Police to enforce strictly the laws against panhandling.

THE curfew was unenforceable; groups of freaks gathered on the Common every night for weeks there after, as if daring the police to try to push them off it. Summerthing ignored the Council's request, as did Harvard. And the merchants, not satisfied, came together again the following Wednesday to try to find out a way to get back to the profitable Cambridge they had known. Stores like Krackerjacks, J. August, Saks Fifth Avenue, and Bobbi Baker Ltd. had been hit hard. Krackerjacks had lost $2400 in windows, and as its manager said, "You have to sell a lot of bluejeans to make up for that." Many of these were little stores, not parts of chains, without big capital to build them back up if they fell down.

"How long can we be passive and turn the other cheek when we get hit?" Bobbi Baker asked, and a lot of the merchants agreed. Jim Jacobs, owner of J. August, said, "I'm not talking about killing the grass, just getting rid of the weeds, that's all."

The merchants selected Alexander Zavelle, general manager of the Coop, as their spokesman. "I think we can clean up the Square without arresting people or beating them up," Zavelle said. "I know kids will call this repression. They call everything against them repression. There has to be a middle ground. I think the merchants feel that things have gone too far one way. They want the balance readjusted. I hope the leaders of the young community will come forward and work with us." He and Sheldon Cohen, owner of the out-of-townNews Agency, began working with City Councilor Barbara Ackerman as the merchants' liaison with the street community. Their early plans included a possible Halfway House for the kids who would no longer be allowed to sleep in the Square or make a living panhandling.

The police, who had been heavily criticized by Cambridge residents for their "low visibility" strategy in the July 25 disturbance, also began to show that they meant business. After every Summerthing concert, five or more patrol cars and dozens of helmeted patrolmen blanketed the Square, prepared to cope with a further outbreak. In the daytime, police moved the freaks selling leather belts and water-pipes off the sidewalk, and several arrests were made. Radicals hawking the Old Mole and Juche (the free publication of the People's Community News Service) were repeatedly threatened with arrest and told to clear our.

AND the Square grew bleaker. Most of the stores boarded their windows and kept them that way. The tension grew, and rumors raced around. Worried merchants called each other with the latest predictions: a riot was set for tonight; massive trashing could be expected after the concert; there were Panthers with guns in town.

At the like and Tina Turner concert in the Stadium, State police swarmed around the gates and mounted police occupied every corner. As soon as Tina Turner finished her set, she was escorted to her trailer by a phalanx of blue-helmeted troopers. The crowd howled in dismay. Purse-snatching and muggings increased.

But the next disturbance did not come until August 7. Again, a mysterious message summoned Cambridge freaks to a "block party" on the Common. This time it was a brightly colored poster on the boards in front of Cambridge Trust purporting to be from a group of women who "dig NLF women." Studded with quotations from Bobby Seale and HueyNewton, it gave no particular reason for the planned action, but warned darkly that some people in the Square were attempting to prey on street culture. It asked the freaks to bring rocks, sticks, and bottles to "run in the streets" for an "outtasight night."

Again, some Cambridge radicals smelled a trap, and began circulating the word that the planned action might not be the smartest in the world. Nevertheless, by curfew time about 150 people had gathered on the Common and trash bonfires were burning brightly.

But the crowd was not solidly convinced that running in the streets with sticks, bricks, and bottles would be a stone groove on this particular night. In fact, all but about 25 were there to attempt to defuse the situation. The debate raged out from the Common onto Mass. Ave. where some began tearing down the parking rails in an attempt to build rudimentary barricades.

"C'mon, let's go to the Square!" one shouted.

"Why?" somebody else yelled.

"Ah, man, I need a new shirt," the first answered.

Someone asked another white youth why he wanted to break windows and fight cops.

"Well, look, man, when I was here last time-"

"When was that?"

"April 15. Man, when I was here, those pigs beat on me. I want some revenge."

One kid uprooted a parking meter and began bouncing it on the pavement, trying to break the coin box open. This was too much for the policemen waiting near the Square. Suddenly, at a signal, Mass. Ave filled with cops firing tear gas canisters.

"They came from out of nowhere," one kid said later.

BUT not exactly. Where they had come from, in fact, was Harvard Yard. The cops had been stationed in the Fire Station waiting for the call, and when it came, they moved right through the Yard and out onto Mass. Ave. Harvard Police Chief Robert Tonis later said that the police entered the Yard "through the fire gate by cutting a lock." They marched through the Yard to the Gate by Harvard Hall, where a University policeman unlocked the gate and let them out. Tonis said that the Cambridge Police "felt it was a necessary tactical movement to prevent injury to the men." The Police Department refused to make any comment.

The outflanking maneuver was an outstanding tactical success. Panicked by the magical appearance of the men in blue and the quick firing of nearly a dozen tear gas canisters, the crowd panicked and ran, splitting at once into a mob of discrete individuals. Any sense of unity that might have remained was lost; it was time to get out quickly. The police succeeded completely in controlling the action and keeping it away from the Square, where windows might be broken and more unfavorable publicity generated.

The police relentlessly pursued the crowd up toward Radcliffe, blocking off all entrances to the Square, redirecting traffic, and announcing an 11 p. m. curfew. A few windows were broken up Mass. Ave. and one car was set afire, but the disturbance was fairly well dampened before it ever caught on.

Although pleased by the quick police reaction, the merchants still reacted strongly to this latest disturbance by demanding more police presence in the Square-demanding, in fact, a general police crackdown on street people in the Square.

Gone was the idea of liaison, of a Halfway House. The merchants, some of whose losses could be counted in the tens of thousands, wanted the Square cleaned up now. Trapped in a nightmare which seemed to promise street violence escalating in frequency and intensity, they wanted police action.

"We asked police to start redressing the balance to some extent," Zavelle said. "It amounts to saying, 'Kids, if you don't have something definite to do here, you'd better leave.' I don't enjoy saying that," he added.

The merchants put increased pressure on the police, who responded by conducting two quick raids on the Common after dark. In both raids, uniformed plainclothes police, backed by squad cars, entered the Common, made arrests for possession of drugs, and left quickly. Several youths were beaten with clubs during the raids.

The police also increased their pressure on panhandlers and underground newspaper hawkers, and often stopped longhairs and demanded identification.

The merchants seemed to bear this with good grace. "Most people would rather see a blue uniform than someone out of his mind on drugs," Zavelle said.

The coming of Fall seemed to promise some respite from the daily tension of the confrontation between street culture and commercial demands, as street people began to leave and well-heeled Harvard students-the Cambridge merchant's best friends-began to filter back in. But nobody was willing to make long range predictions. The police and the merchants seemed to be increasingly willing to use whatever means were required to transform the Square into a safe place for business. Talking to two longhairs at the end of the summer, one Cambridge policeman, not unsympathetic, seemed to put it best.

"You guys don't have a chance," he said.