While battalions of Boston police held 3500 antiwar demonstrators at bay outside the Sheraton Hotel last night, Vice President Spiro T. Agnew jumped back into his own battle with the media giants before 2500 members of the Middlesex Republican Club.

The demonstrators had gathered near dusk at Copley Square and marched down Boylston Street to the hotel hoping to meet the Vice President as he drove in from the airport. Agnew, however, arrived early, skirted the crowds and managed to avoid all but a single encounter with the people and the war.

Helmeted Boston police swarmed through the lobby of the hotel, lined the front with mounted officers and canine squads, and gathered in groups of five and six around the entire Prudential Center Complex.

Hardhats

The group of protesters grew from 500 to 3500 as they marched down Boylston and turned the corner at the front of the Sheraton. When they arrived, five antiwar construction workers wearing their hardhats swaggered out from the center of the crowd and strode ahead of the surging crowd toward the hotel entrance.

Mounted police pushed them back, then dodged scattered rocks and bottles as the protesters retreated about 20 yards away for speeches denouncing the Vice President's "unmitigated nerve to come to Boston."

The Vice President no doubt did not hear, as he stood in a fund-raising cocktail party greeting Massachusetts party regulars.

Agnew, emerging from nearly six months of silence since his campaign attacks on GOP liberals, found new life for an old theme-the irresponsible dominance of the national media-as he addressed the dowagers and donators in the Sheraton's Main Ballroom.

However, examples of both the police-student encounters outside and quiet liberal indignation inside, couldnot help but seep into the evening's program.

At one point in Agnew's own speech-just as the Vice President denounced media coverage of "Any extremist who dignifies our adversaries and demeans our traditions" and "unloads into millions of American living rooms his deprecations against society and disrespect for civilized law," -shaggy-haired c. Wendell Smith, 28, a reporter for the Phoenix, rose to glare at the Vice President from the center aisle.

Agnew hesitated for a moment, then police guarding the podium rushed toward Smith and dragged him from the ballroom, as Agnew told the applauding audience to "see where the cameras are going."

Outside, police had already dispersed the crowd away from the hotel entrance, pushing them back down small streets and onto Boylston with police reinforcements.

On one small sidestreet-Scotia Street near the Cheri theatres-policemen broke ranks and ran after demonstrators who had either lagged behind or fallen down. They struck about seven people with clubs, shoving one up against a brick wall and back to the street, hitting him repeatedly on the neck and back.

After about 20 minutes of police charges most of the crowd had dispersed into relatively small groups. While about 250 headed for a teach-in at B.U., a number of small groups roamed the streets randomly throwing rocks through windows. Police last night reported 13 broken windows.

The police last night arrested 15 on charges of disturbing the peace. Two of those arrested were charged with assault with a dangerous weapon. They were accused of stoning the police and attacking one officer with a club.