Today in history:On Sept. 20, 1973, in their so-called “Battle of the Sexes,” tennis star Billie Jean King defeated Bobby Riggs in straight sets, 6-4, 6-3, 6-3, in the Houston Astrodome. (Magellan was killed en route, but one of his ships completed the first circumnavigation of the globe three years later.) In 1967, the Cunard liner Queen Elizabeth 2 was christened by Britain’s Queen Elizabeth II in Clydebank, Scotland. In 2011, the repeal of the U.S. military’s 18-year-old “don’t ask, don’t tell” compromise took effect, allowing gay and lesbian service members to serve openly. Author George R. R. Martin is 77.