When developers announced they would build a shopping mall next to the Manassas National Battlefield Park, activists in western Prince William County promised a fight. So far, they've been as good as their word.

One lawsuit has already been filed to block Hazel/Peterson Cos.'s planned 1.2-million-square-feet shopping center at William Center, next to the national park, near Rte. 234 and I-66. And another is apparently on the way.

On top of that, two members of Congress have sent a letter to U.S. Transportation Secretary James Burnley asking him to exert his agency's influence in blocking the proposed mall, a joint project between Hazel/Peterson and the Edward J. DeBartolo Corp.

Taking the first blow in what is likely to be a volley of litigation, Frederick D. Greco, a Catharpin resident and Fairfax County lawyer, filed suit last week in Prince William Circuit Court against the Board of County Supervisors. He is asking for an injunction to prevent the start of construction on the mall.

Mall opponents have charged that a shopping center on the William Center site would irreparably damage the national park, bringing excessive traffic, noise and visual blight to the area. The critics contend that the William Center property does not have appropriate zoning for a shopping center.

The property was rezoned in November 1986 as a mixed-use development. At the time, Hazel/Peterson officials said the project would be primarily a corporate office park, similar to the company's Fair Lakes complex in Fairfax County.

Many civic activists now fighting the mall supported Hazel/Peterson's rezoning, reasoning that an office park was less offensive than other development possibilities at the William Center site, which is where Confederate Gen. Robert E. Lee had his headquarters during the Battle of Second Manassas.

Although Hazel/Peterson changed the emphasis of William Center from offices to a shopping center, supervisors have said that the firm does not need to seek a new rezoning to proceed with its plans.

Greco's lawsuit disputing this will likely be matched by one filed by the Save the Battlefield Coalition, a group organized in the last three weeks to fight the Hazel/Peterson proposal.

Anne Snyder, coalition chairman, said the group has raised more than $6,000 and recently hired two prominent land-use lawyers, Tersch Boasberg of the District and Franklin R. Reynolds Jr. of Rappahannock County, with the expectation of filing suit against the county soon.

The mall opponents have said their best hope for blocking the shopping mall may rest with the federal government.

Two Democratic representatives, Robert J. Mrazek of New York and Michael A. Andrews of Texas, wrote Burnley last week saying, "We hope to enlist your support in saving this important site from destruction."

Mrazek and Andrews contend that federal law prevents the construction of transportation projects that would have an adverse impact on historic sites and parkland. Without an interchange at I-66, a shopping mall at the William Center site would likely be infeasible.

Hazel/Peterson officials have said that the William Center shopping center would not harm the national park and would produce millions of dollars in tax revenue for Prince William.