Jean Compton, homemaker, bookkeeper and mother of two, recently climbed onto the roof of Culpeper's waste water plant and stood guard for two hours.

Dressed in a military uniform she bought herself and armed with a borrowed rifle that wasn't loaded, the 36-year-old Compton was on the lookout for "attackers." None came.

Her guard duty, which Compton described as "a small way of serving my country," was part of an "antiterrorist" training exercise for the Culpeper-based H Company of the Virginia State Defense Force, an unpaid militia of about 1,800 volunteers set up three years ago under the slogan "Virginians Taking Care of Themselves."

Similar to the Virginia Protective Force that existed during World War II, and organized as the light infantry "George Washington Division," the state defense force is intended primarily as a constabulary. Its main purpose is to take over the state's 53 armories if Virginia's National Guard were "federalized," an event that last occurred in 1940.

"There's been no need for it in the past 40 years, but that's not to say there will not be need for them in the future," said Brig. Gen. Herbert L. Turner, commander of the force's Staunton-based 3rd Brigade. "What's sitting down there 90 miles off the coast of Florida? It could be a launching pad, couldn't it?"

Any Virginian over the age of 17 who is not eligible for duty in the National Guard can volunteer for the force and serve indefinitely. However, Division Commander Gen. Alfred Ross Morris, a 68-year-old retired National Guard officer "working on 52 years in uniform," said the force appeals mainly to retired military personnel, something Virginia has in abundance.

"We sometimes call it the bone-yard brigade," he said during a recent interview in Richmond. "We're old people, but there's a certain amount of military gray matter based on years of experience." Retired military personnel "miss it since they left it," he said. "It's an orderly way of living."

The force, which reports to Virginia's highest military authority, Adjutant General John G. Castles, includes an aviation brigade of 72 planes and a 40-vessel maritime brigade, all privately owned craft. Among its duties, according to its latest training directive, are to "meet domestic emergencies . . . provide external physical security of key facilities . . . maintain law and order, suppress riots or insurrection . . . {and} assist . . . preventing or suppressing terrorism."

Last year, the legislature increased its budget from $61,000 to $136,000, mainly for administrative costs and for the salaries of seven part-time employes in its head office in Richmond. (Volunteers are paid only when mobilized by the governor.)

Virginia's state defense force is part of an increasing effort by the nation's governors -- encouraged by the Department of Defense -- to create backups for their National Guard units in the event they are called to active military duty.

The effort may get a boost if Congress passes a pending bill that, for the first time, would supply these forces with surplus military uniforms, weapons and equipment.

"There's been an impetus {to create state defense forces} since 1970 because the National Guard is becoming more a part of the total force than in the past," said Maj. John Smith, spokesman for the National Guard Bureau, which monitors the state forces. "There is forward momentum happening out in the states. We're going to see a positive growth."

The 550,000-strong National Guard makes up 46 percent of the Army's combat forces, he said. Because Virginia and Maryland's National Guards form one of the Army's four light infantry divisions, they would be among the first called, Smith added.

Virginia's is the largest of the 23 existing state defense forces, whose combined strength is 10,000, according to the bureau. Texas' 1,500-strong force has existed since 1940, making it the oldest in continuous service; California's force has 1,400 members, while Maryland's has 156.

In a recent directive to the states, the bureau said that any future federal support would go to those defense forces organized as a lean unit that could be quickly expanded in the event of an emergency. They recommended that the permanent unit be equal to only 10 to 15 percent of a fully expanded force.

As a result, Castles recently ordered a reorganization of Virginia's defense force that will result in a reduction to about 900 members, a change in uniform markings for the third time since the force was created, and a disbandment of its maritime brigade, according to Morris and other sources.

Castles has told Morris the changes are necessary in order not to jeopardize future federal support, sources said.

Morris said the reorganization has forced him to cancel a major recruiting drive set to begin this month. "Picture my consternation," he said, "when I was told they want to keep the force" at 900 volunteers. "They're coming in from everywhere -- I already have 1,800. What do I do with the surplus . . . ? Who do I determine to keep and get rid of?"

But Morris said the reduction would be by attrition. "We'll drive nobody away," he said.

Despite the rapid expansion of Virginia's defense force and enthusiastic participation in the rank and file, some current and former officers say they are frustrated by high turnover in some companies, disorganization in the outfit and inappropriate training for the volunteers.

Declining to be identified, they criticized the number of high-ranking officers in the force (there are 16 generals; a military division usually has three), delays in sending out commission letters to officers and IDs to new volunteers, as well as training that does not fit a constabulary force. These problems have led to the recent resignation of at least one high-ranking officer, they said.

National Guard recommendations stipulate that training should be "interesting and realistic." But when 20 members of the 3rd Brigade's 2nd Battalion met last week at the Manassas armory for their monthly eight-hour drill, they were given a course in "cover and concealment." They were instructed how to use greasepaint and camouflage themselves in the woods -- skills not likely to be necessary for a constabulary force.

A training directive sent out this month orders that volunteers be instructed in map-reading and the use of a "field telephone." "They don't use field telephones any more," said one officer who declined to be identified. "And the only map these people will have to read is a road map."

A major failing, say some critics, is the lack of weapons training. Although such training is promised in an advertising brochure, the force does not have weapons. "That's obviously a big thing," said defense force Capt. Mark Moorstein, a lawyer. "Because if you really have a national emergency, you'll have people shooting at one another.

"I don't know if anybody could even find weapons around here," he added, looking around the Manassas armory.

Morris acknowledged that camouflage training is inappropriate. And he attributed any disorganization to the fact that "the first conception {in 1984} was one of a bit larger force . . . than now seems to be the case." He said he would soon send out letters of commission, and added that the top-heaviness in the number of officers is because "we will maintain only a cadre" force.

Norfolk tugboat captain Fred Tinkle, a member of the maritime brigade, said there is some friction with the Virginia National Guard, which he said "views the state defense force with extreme jealousy -- they think we're going to move in and take over."

These problems, however, did not seem to bother the 30 volunteers of H Company who showed up for their recent training exercise.

The company commander, Capt. William Jagdman, said there was some criticism for choosing Culpeper's waste water plant, not generally considered a key facility. He did so, he said, because its 90-acre fenced grounds resemble "a small nuclear power plant."

Jagdman, 55, a video store manager, said he tried "to make {the exercise} as close to reality as possible." With this in mind, his volunteers mustered up about six or seven rifles, including some fake ones, to share. They ate Army rations of Spam, crackers, pudding and chocolate-coated peanut butter candy, and broke with reveille at 6 a.m.

Although they had leaked word of their exercise to fellow companies in the hope they might put H Company's security precautions to the test, "we weren't hit," Jagdman said. "We were really disappointed."

"If we're ever called on to do anything it's going to be this . . . to guard something," said Jagdman. "We're not going to be in foxholes. If that happens, we're in real trouble."

Jagdman, who served in the Army for five years, said he joined the state defense force partly because "I just wanted to get back into uniform. I enjoy the military . . . . It seems like we've come full circle from the Vietnam era. I've noticed a lot of people said they want to do something for the state.

"We had a great time. We try to do that, too . . . . When you're working for no money, you got to have some fun."