Fifty years ago on November 22, 1963, in Dallas"s Dealey Plaza, John Fitzgerald Kennedy, the 35th President of the United States, was assassinated while traveling in a motorcade with his wife, Jacqueline. LIFE magazine, the weekly pictorial chronicle of events in America and throughout the world, was quickly on the scene. The Kennedys had been our story: Jack and Jackie made the cover in his sailboat before they were married and he was a fresh-faced senator from Massachusetts, and the White House doors had remained open to LIFE throughout his presidency: Cecil Stoughton"s photographs of Caroline and John-John in the Oval Office, Jackie"s tour of the renovation, tense behind-the-scenes moments during 13 days of the Cuban Missile Crisis-all of this appeared in LIFE. We needed to be in Dallas. The famous Zapruder film first appeared in LIFE, after being acquired by LIFE"s Richard B....