Four members of the United Daughters of the Confederacy and the president of the Virginia division of Children of the Confederacy marched on the office of Sen. Harry F. Byrd Jr. (Ind.-Va.) yesterday in an unsuccessful effort to get Byrd to support a proposed 1,750-acre expansion of the Manassas Battlefield National Park.

During the brief meeting, Byrd reaffirmed his belief that the views of the Prince William County Board of Supervisors, which oppose the expansion, should prevail, according to Jeaniene Dibble of Manassas, historian of the United Daughters.

The delegation thrust upon Byrd a letter written by his late father, Sen. Harry Flood Byrd (d-Va.) on June 6, 1935, in which he encouraged then Secretary of the Interior Harold L. Ickes to establish the original national park, but his father's position did not sway the senator yesterday.

Mrs. Dibble said supporters of expansion fear that if the federal government does not buy the land for the park, it will be subdivided for tract housing.

The land involved, according to Mrs. Dibble, is where "on Aug. 28, 1862, Stonewall Jackson saw Rufus King's division of McDowell's forces comingdown Warrenton Turnpike, and without waiting for Lee's approval, charged, although his forces were greatly outnumbered. It was the beginning of the second battle of Manassas."