I was saving this picture for July 15th, because that's the date Kennedy accepted the nomination of his party to run for president. But--oops--that speech was given at the Coliseum, not at the Biltmore, 49 years ago today.
Kennedy debated his rival Lyndon Johnson at the Biltmore Hotel during the convention, though--on July 12. (Missed it by that much, and Maxwell Smart would say.) I think this picture is from that date.
The Los Angeles Times reported that the debate turned into "two campaign speeches bridged by admiration, affection and a few padded quips." They were right; Kennedy opened by saying he wouldn't argue with Johnson, because "I don't think we disagree."
Johnson came back with "I can agree with every word Senator Kennedy has said."
A veritable love-fest.
The debate was televised, and those present--jammed into the ballroom--included the sizable Texas delegation, so Johnson drew the most applause. That's not the same as winning, though.