Explore items in the Smithsonian's collections related to 1973. To start the year, the Watergate scandal continued to unfold with a trial of the Watergate burglars beginning less than two weeks before Richard Nixon was inaugurated for his second term. The U.S. ended its involvement in the Vietnam War with the signing of the Paris Peace Accords. In February, Native American activists occupied the South Dakota town of Wounded Knee to demand that the U.S. government make good on treaties from the 19th and early 20th centuries. In May, Skylab, the United States' first space station, was launched into orbit. In September, Billie Jean King and Bobby Riggs competed in “The Battle of the Sexes” exhibition tennis match. In October 1973, an OPEC oil embargo triggered an energy crisis as Americans queued in long gas lines. In November, NASA launched the Mariner 10 Mercury probe spacecraft. At the end of the year, the Endangered Species Act of 1973 was passed to protect critically imperiled species from extinction.