All last week, under a cloak of darkness, men with guns and walkie-talkie guarded other men who carried secret files, weapons, bullet-proof vests and exotic communications hardware out of FBI offices downtown and trucked them to a lonely spot on the banks of the Anacosta River.

The guards were FBI agents riding shot-gun for professional movers transporting the Washington field office, the FBI's thrid largest, to the top floors of a controversial federal office building at Buzzard Point in Southwest Washington.

Employees of several other federal agencies have refused to go there, triggering a tangle of legal proceedings and congressional hearings and branding the buildings a bleak and isolated governmental white elephant.

The FBI went to Buzzard Point virtually without a struggle.

The reasons are linked with the law enforcement agency's traditions of pride and discipline and with the plain fact that "there wasn't much choice, anyway," according to the boss.

The Old Post Office building at 12th Street and Pennsylvania Avenue NW, where the field office has been located for more than 26 years, had become "filthy" and "squalid," infested by roaches, bats and rats, and a leaky firetrap, "the worst space in government," according to Nick F. Stames, special agent in charge of the field office. He said he had been determined to make a move since taking over 2 1/2 years ago.

"We're a proud organization," he said, "and the old offices made it hard for us to be proud."

"Some employees expressed opposition to the move at first. Stames acknowledged. But he said he could not understand the idea of Uncle Sam's troops balking at an order. Personally, he also would prefer a "nice location up on Connecticut Avenue," he said.

"But I've got 25 years with the FBI, and I don't remember ever being asked where I wanted to work," he said.

Stames suggested that employees of other agencies should take the same attitude or quit.

An FBI man came in to cut the cable on Stames' specially "enerypted" (Scramble-coded/ telephone, used for communications with certain other government agencies, so that it could be moved out of the fading, mahogany-paneled, high-ceilinged office to its sterile, low-ceilinged new home.

In the outer office, boxed files and FBI sports trophies were stacked. Desks and chairs all had masking tape labels, indicating their new room numbers.

Part of the problem with Buzzard Point is pyschological; it's in the name, Stames mused. "Reminds people of an animal that thrives on dead meat. They should rename it Peacock Lane or something."

"For now, he said, "We call it "The point."

The FBI's Washington field office employs almost 700 agents and supporting staff members. Their most prominent recent case files include the series of phony fencing operation here in which they joined D.C. police and other fedeal agents, went under cover and caught theives, loot and a publicity bonanza.

There also was the kidnaping of Alan Bortnick, in which a $100 ransom bill helped crack the case, and the car bombing on Sheridan Circle NW a year ago that killed former Chilean Ambassador Orlando Letelier and a Washington woman. That case is unsolved.

In addition to kidnapings, extortions, counterintelligence activities and such, and because of Washington's embassy community, the field office's duties here include protection of foreign officials and guests.

The official price tag for the field office's move is $23,000, according to the General Services Administration. The move would have cost considerably more if the FBI had gone ahead with a plan to install a special underground telephone cable linking Buzzard Point with the J. Edgar Hoover Building, the FBI headquarters downtown. The plan had fueled criticism about the building's location and the FBI move.

The FBI decided that the cable's cost was prohibitive and that the cable would have taken too long to install and would have involved tearing up streets. Stames said. As a result, "we are no longer on the 324 telephone exchange - that's FBI initials. Now we're on 252. It's not as convenient, but it was necessary."

Bureau headquarters had moved it civil fingerprint files to Buzzard Point last spring, noting cramped conditions in the mamoth, $126 million Hoover building completed two years ago. An FBI spokesman blamed the space crunch on a mushrooming staff due to agency attempts to keep pace with information requests under the Freedom of Information and Privacy acts.

Many field office agents and staff members said they are resigned to, but not thrilled about, the move to "The Point."

"Sure it's a nice building, but it's just too far out," said Marilyn vaugh a clerk. She stood with a group of co-workers in an empty expanse of new-smelling office, gazing at their new view of the Anacostia River and waiting for their old desks to arrive.

Some employees expressed concern about lack of public transportation to the building. Vaughn and some others temporarily catch a mail shuttle from FBI headquarters when space is available, they said. Plans for improved Metrobus service are uncertain.

They also grumbled that there are no shops and little to do at lunch time. Except for another, older federal building nearby and a small marina, the location is surrounded by fenced-in acres of high-voltage Pepco power equipment, warehouses, overgrown vacant lots and rubble.

It is said that the only night spot in the area is a gay bar, and with the straigh-arrow FBI moving in, as one Buzzard Point worker put it, "We expect that out of self-consciouness, if nothing else, they'll have to either move or change."

For Mildred, C. (Millie) Parsons, a FBI secretary, the move to Buzzard Point is welcome but "drastic, almost like starting a new job."

Parsons has worked 38 years for the agency and has the distinction of never having taken a single hour of sick leave. Stames is the 18th special agent in charge for whom she has worked.

She was on hand when the field offied was moved into the Old Post Office building in 1951, a move supposed to be "temporary," she noted.

The 9-year-old romanesque revival structure, with its familiar clock tower, has a huge interior air shaft surrounded by nine stories of offices. "I remember not long after we moved in, a man tried to throw himself over the brass railing of the fifth-floor balcony," Parsons recalled. "Our agents stopped him."

Some of the offices there seemed more like a hideout of crooks than a hangout for police, according to some staff members. "I once arrested a suspect, and when I tried to bring him in here, he kept asking to see my credentials. He thought he was being kidnapped," said special agent Joseph E. Dowling, as he pointed to a grim "interview room" whose walls were grumbling and staines with paint peeling and rusty pipe exposed.

In line with the planned development of Pennsylvania Aveenue NW, the government plans to modernize and preserve the Old Post Office building for cultural, recreational and commercial activities as well as federal offices. "Yeah, now that we're leaving, they're going to fix it up" one FBI man noted bitterly.

THe painful history of the Buzzard Point flap was set in motion in 1974.after the Securities and Exchange Commission requested more space. GSA leased the building despite SEC objections, and SEC became the first of at least four agencies that declined to move there.

City officials, the National Capital Planning Commission, several citizen's groups and employee unions are among those that have opposed lease of the building by GSA.

Federal employees have contended that, besides lacking public transportation, the location is short on parking and eating facilities and presents a high crime risk.

A cafetaria is scheduled to open in the building next month, according to FBI research in the neighborhood, crime should not be a problem, Stames said.

It is unclear who will join the bfbi to fill the remaining empty floors at Buzzard Point. A task force of the president's reorganization team is occupying a floor temporarily. Speculation is that some Department of Defense workers now at the Forrestal Building will be moved there to make room for the new Department of Energy.