Congress has voted to create a federal commission charged with coming up with a national policy on protecting Civil War battlefield sites.

The commission would identify and rank all Civil War battlefields and make recommendations on how to preserve key sites, under a bill passed early yesterday as Congress rushed to adjourn.

President Bush is expected to sign the bill, which also calls for a specific study of Virginia's Shenandoah Valley, where there are no national battlefields, though it was the site of two major Civil War campaigns, said Interior Department spokesman Steven Goldstein.

Supporters said the bill is designed to prevent the kind of bitter and expensive battle that erupted two years ago over a plan to build a shopping mall next to the Manassas National Battlefield Park, and which resulted in Congress seizing the land.

"Having fought the battle to protect Manassas, I know how difficult it is to protect Civil War sites on an ad hoc basis," said the bill's Senate sponsor, Dale Bumpers (D-Ark.). "This commission is intended to give Congress a priority list to work with."

The legislation comes as development across the country threatens to engulf many battlefields, especially in Virginia, where almost half the 129 major sites listed in a recently published directory are located.