The latest skirmish in what might be called the fourth battle of Manassas occured yesterday. It took place at a Senate subcommittee hearing and the opposing forces included Rep. Herbert Harris (D-Va.), two Interior Department officials and abour 30 angry Manassas residents.

Most of the residents, many of whom came by chartered bus, said they favor commercial development and oppose the expansion of the Manasses National Battlefield Park proposed by Harris.

A bill sponsored by Harris authorizes the Interior Department to add 1,500 acres, most of it now farmland, to the present 3,000-acre park.

Land would be acquired by purchase from owners willing to sell. Other property owners would be paid for scenic easements - agreements that the land will be kept in its present state and no more buildings or other structures will be added.

Harris's bill also would provide about $200,000 to Prince William County as compensation for lost tax revenue.

But the citizens - most of whom are residents of the battlefield community neighborhood, which is unaffected by the bill - were hostile. They claimed that the bill will mean expropriation of their homes by the Interior Department for an ever-expanding park.

They are equally upset, they said, that the use of the acreage as parkland would preclude commercial development, something they contend Manassas sorely needs.

Donald White, vice chairman of the Prince William County Board of Supervisors, angrily told the Subcommittee on Parks and Recreation chaired by Sen. James Abourezk (D-S.D.): "This isn't going to help people. The (federal government) can't continue to ... take land from the county ... (you're) taking land off the tax rolls."

White said that 24 per cent of county land already is owned by the state or federal governments.

Betty Duley, an organizer of citizen resistance to the bill, said she vigorously opposes the Harris bill because "we don't trust them (the Interior Department). What does scenic easement mean? It means one thing today and another 10 years from now."

A Harris aide said some of the citizen's mistrust stems from a misunderstanding. In House hearings last spring, an Interior Department representation said the agency would like to acquire 600 acres in addition to the proposed 1,500.

Although Harris testified he "flatly opposes" these acquisitions, the aide said, many residents voiced a fear that the Interior Department's wishes become reality.

Harris's bill was blocked last year by a last-minute objection by Sen. William L. Scott (R-Va.).

An aide to Sen. Harry F. Byrd Jr. (Va.). said Byrd and Scott have asked the subcommittee to delay action on the bill this year pending a survey of community attitudes by the Interior Department.