Leontyne Price sang "The Battle Hymn of the Republic" up to the last rows of Constitution Hall last night, dedicating her performance before 3,500 Daughters of the American Revolution to her friend, Marian Anderson.

"I think it's a positive end to a chapter of American history," she said after a performance that left many dazzled.

No one at the opening session of the DAR's 91st annual congress had to be reminded of 1939, the year the organization refused to let Marian Anderson sing at Constitution Hall because she was black. This year, Price, who is also black, was invited with Anderson, although Anderson was ill and had to stay home.

"Miss Anderson is here in spirit," Price said.

The DAR, which for years has been fighting its racist, old-lady image, was not inclined to cast the performance as a good public relations move. "Miss Price was invited because she is the greatest artist, and because she is a fellow Mississippian," said DAR president general Patricia Shelby, who's from Beulah. "The fact that she is a close friend of Miss Anderson's was unknown to me. And Marian Anderson has sung eight times in Constitution Hall since 1939."

Price's performance, which included an aria from the opera "Tosca," was but one portion of the nearly two-hour-long opening session of the congress. Flags! Ribbons! Accolades to the Daughters, "the finest ideals of American womanhood!" Acclaim for the U.S. Constitution, the "immortal emblem of humanity!" Pearls! Minks! Orchid corsages!

Some were the size of heads of bibb lettuce. But then, nothing is small at the DAR's opening night. An enormous American flag came sweeping out from the ceiling to rousing music. A letter from President Reagan was read. Former senator Margaret Chase Smith called for a new military draft, deeming the volunteer system a "tragic failure." The women applauded, all dressed as if they planned to dance at the palace.

"No, we don't do it to impress anyone," said Elizabeth Duffill of Danvers, Mass., acknowledging there were only a few men around to notice the thousands of new hairdos and taffeta skirts. "It just makes us feel good."

The Daughters will be in Washington until the weekend. They'll be listening to reports from their state regents, commemorating George Washington's 250th birthday and voting on resolutions on subjects ranging from "Marxism in U.S. Classrooms" to "Perversion of Moral Values Through Education" to "Taxes" to "The Metric System."

They say there will be no platform debates, no squabbles over policy and no disagreement over issues.

"We just don't fight among ourselves," said president general Shelby of her patriotic and service organization, which has 208,000 members who trace their lineage to the American Revolution.

But there will be shopping and sightseeing. The husbands do a lot of that. Many wear buttons that say "HODAR"--for "Husband of a Daughter of the American Revolution."

This prompted one questioner to wonder last night if the husbands are henpecked.

"Heavens, no," said Adlyn Stein of Cleveland. "My husband owned nine corporations. He was in the National Foootball Hall of Fame. He wasn't a slouch."