When Ian Smith, the controversial Rhodesian prime minister, came to Washington last fall, he shunned the fashionable Madison and Hay Adams hotels that many visting heads of state prefer.

Instead, Smith and his party headed directly from Dulles International Airport for a sprawling stone mansion overlooking the Blue Ridge Mountains 65 miles southwest of Washington.

It was the same place that Army Gen. John K. Singlaub headed for when President Carter fired him for criticizing the president's planned troop withdrawals from South Korea.

Smith, who visited here, and Singlaub, who got a public speaking job here, joined a parade of hundreds of congreesional aides, retired military officers and corporate executives who each year come to this tiny, bucolic hamlet to talk about the Pentagon, Moscow, and ultimately, World War III.

For this is Boston, Va., home of the American Security Council, a place where the Cold War still rages.

Boston, Mass., may claim to be the home of the American Revolution. But in this Boston, which comprises little more than a post office, several churches and an American Legion post, the Russian revolution is a constant topic.

Council president John M. Fisher, who was a World War II bomber pilot and whose offices sit on a rolling, 850-acre former estate, puts it this way: "Here, we are interested in communism with a capital C."

His press liaison, former Newsweek foreign editor Philip C. Clarke, puts it more lightly. Directing a visitor to go a few miles west of Culpeper up a country road to a pair of imposing brick pillars, he says with a chuckle: "It's the last left turn you'll make."

Inside the estate is a complex once billed as the nation's only private Cold War college. It has seminar rooms, plush dormitories and offices from which a staff of 30, using computers, generates millions of mailings each year on behalf of the council and its tax-exempt arm, the American Security Council Education Foundation. Each mailing carries the same message: Moscow is winning the Cold War.

It is, of course, a controversial message and one that draws frequent criticism from Pentagon and administration officials. But it wins praise from the right.

"They're very sharp activists," says William Rhatican, an associate of Richard A. Viguerie, the direct-mail wizard of conservative causes. "They're respectable both in terms of the New Right and Capitol Hill."

Indeed, the council has put together a group of 140 congressmen called the Coalition for Peace through Strength to oppose the current SALT talks results, and the council's masthead is peppered with distinguished names and a gleaming list of polished brass.

The leadership once included former Virginia governor Mills E. Godwin, and now claims several former chairmen of the Joint Chiefs of Staff, ex-ambassadors, corporate executives and professors. One staff member professor from Havana who once flunked Fidel Castro in history.

"They're not kooks," says Wes McCune, who watches the right for the left through Group Research, a Capitol Hill-based operation. "They're the cold warriors. I just plain call them The Military-Industrial Complex."

Perhaps because of its prominent leadership, the council recently has avoided the extreme right image of groups like the John Birch Society and the Liberty Lobby that are "still looking for a communist under every bed," according to council member Elbridge Durbrow, a U.S. ambassador to Vietnam from 1957 to 1961.

But the red-under-the-bed syndrome was not too far distant in the council's past. Originally founded in Chicago in 1955 as the Mid-American Research Library, the council's intial function was to compile files on suspected communists who might apply for jobs at large corporations. The first council members included Sears, Roebuck & Co., where Fisher worker until 1961, Motorola Inc., and Marshall Field & Co., but grew to include more than 1,500 employers.

In 1972, the council finally phased out its Chicago library, then believed to be America's largest private file on the political beliefs of individuals, and Fisher announced the council was shifting its focus to international security and nuclear strategy.

But the personnel records, which ran to over 6 million file cards and which a 1960 council brochure called a "specialized subversive activities library," were moved to Boston, Va., where the council was trying to set up its Cold War college.

Newspaper investigations in the 1950s said that many of the files had been purchased from sources such as Harry Jung, a right wing publisher known during the 1930s for anti-Smitic and antilabor sentiments. Fisher told a reporter in 1961 that he had tried unsuccessfully to obtain the files of the late senator Joseph R. McCarthy, R-Wis., whose anti-communist tactics earned the censure of his Senate colleagues.

The personnel files are still here in Boston in the council's Sol Feinstone Library for the Survival of Freedom. Fisher says few requests for their use come in. A reporter who asked to wander in the stacks was allowed limited access only when escorted by the resident library director.

The personnel files were not shown to the reporter.

Mostly, the council has tended to stir squabbles over its hawkish politics, as was the case in 1970 when it launched Operation Alert, a national campaign that sought to discredit six U.S. senators up for reelection on the basis of their national security voting records.

One of the senators, Maryland Democrat Joseph D. Tydings, was the subject of a particularly vitriolic campaign that used extracts from Operation Alert newspaper ads. Both he and New York Republican Charles E. Goodell lost their races, but what impact the ads had is questionable since the four other senators won reelection.

There was a brief stir in 1970 over whether the council should have to file contribution reports as a political organization under the Federal Corrupt Practices Act, and the post office that year accused it of abusing cheap mail rates accorded its tax-exempt arm when it mailed out more than 1.5 million pieces of literature before the election. The council prevailed on both points; never having to file as a political group and never losing its mailing rate.

And this fall there was a flap when Fisher and Lt. Gen. George Seignious, former head of The Citadel military college at Charleston, S.C., traded charges after Seignious said he had been lured into the Coalition for Peace Through Strength because Fisher had mislead him about the group's SALT position. Seignious, now head of the Arms Control and Disarmament Agency and the chief SALT negotiator, quit the coalition.

Fisher says council critics are just jealous of the council's professional work, which includes films about what the council deems is the impending Soviet dominance in the arms race.

"They're not bad films," says a dovish aide of the Senate Foreign Relations Committee. "They're really quite slick. What upsets a lot of us is that they're better than ours."