Fifty years ago, on November 22, 1963, former President John F. Kennedy was assassinated while driving through Dallas, Texas, with his wife and Governor John Connally. He was first shot through the shoulder and chest, and received a fatal shot to the head, killing him within thirty minutes.

As the nation was just beginning to reel from shock, Kennedy was rushed to Parkland Hospital, where Dr. Kenneth Salyer, a 27-year-old resident at the time, was on call for head trauma. Dr. Salyer, who said that the president was still barely breathing when he arrived at the hospital, was surprised to find that JFK was wearing a stiff back brace underneath his clothes. Salyer believes if the president hadn't been wearing a back brace, he might have survived the shooting.

"The first shot that hit him went through the soft tissue of the back of his shoulder and exited through his trachea," Dr. Salyer told CBS News. "That same bullet went through [Texas Governor] John Connally's chest, through his right hand and into his thigh and knocked him completely down in the car." Connally, who fell over immediately after being shot, was spared additional bullets and survived. But Kennedy, whose back brace prevented him from slumping over, was shot another time in the head. "He's still upright as a target because he has the brace on, which makes it possible for Lee Harvey Oswald to hit him with a second shot," Salyer told CBS News. "I think that would not have happened if he had gone down like John Connally did."

Kennedy had suffered from back problems for years, experiencing such severe back pain that he even needed assistance in bending over to tie his shoes. He underwent several life-threatening back surgeries and was known, behind closed doors, to be a sickly president. James Reston writes on the LA Times that "Member's of Kennedy's inner circle had often witnessed the painful ritual that Kennedy endured in his private quarters before he ventured out in public, when his valet would literally winch a steel-rodded canvas back brace around the president’s torso, pulling heavy straps and tightening the thongs loop by loop...Once in it, the president was planted upright, trapped and almost bolted into a ramrod posture." When Robert Dallek, an independent historian, conducted an examination of President Kennedy’s medical records, he found that JFK was actually taking a lot of medication for not only his back, but other ailments that ranged from digestive problems and Addison’s disease, which is constituted by impaired adrenaline production and can be fatal.

Though JFK has been criticized for maintaining an image of youth and vigor while hiding his real medical problems, Dallek, writing in The Atlantic, says that Kennedy’s medical records revealed instead the “quiet stoicism of a man struggling to endure extraordinary pain and distress.”