SANTA CLARA, Calif. — The Civil Rights movement had Selma as a touchstone; the gay rights uprising took flight at the Stonewall Inn; and the N.F.L players’ campaign for social justice on Sunday had Levi’s Stadium as its epicenter. It was here last year that Colin Kaepernick took a knee during the playing of the national anthem in protest of racial oppression after several police shootings of black Americans.

On Sunday, it might as well have been Little Big Horn for the home team. The Dallas Cowboys’ 40-10 shellacking of the 49ers was the franchise’s worst defeat since 1980 and kept them winless for the seventh straight game.

Who won the national anthem showdown? It depends on your point of view.

The 49ers’ Eric Reid, who knelt alongside Kaepernick last season, did so again Sunday, as did six teammates, down from about two dozen at the peak a few weeks ago. Every player on the Cowboys, widely known as America’s team, remained upright, no doubt pleasing the team’s owner, Jerry Jones, who said players who disrespected the flag in his view by sitting or kneeling would not play.

Against Green Bay this month, defensive linemen Damontre Moore and David Irving had raised fists at the anthem’s conclusion. On Sunday, Irving raised his fist briefly, and Moore briefly did so, too, but only after the anthem was over.