What happened in the assassination of John F. Kennedy?

President Kennedy insisted on visiting Texas in November 1963, even though his advisers cautioned against it. Texas was extremely hostile territory, with many Texans violently in opposition to Kennedy and his policies. But Texas was an important electoral State for the Democrats in the upcoming Presidential election of 1969, and Kennedy wanted to win over the Texas voters.
Kennedy's Texas itinerary included an open motorcade through the center of Dallas, a particularly virulent anti-Kennedy city, concluding in a rally at Dallas' convention center.
President Kennedy and his wife Jackie were in the back seat of their open limousine, waving to the large crowds lining the streets of downtown Dallas' motorcade route. Just after the motorcade made the sharp turn into Dealey Plaza, it slowed down. Oswald fired. President Kennedy was shot in the upper spine area and head, from the rear. The first bullet that struck the President passed through both JFK and Governor Connally. It went through Kennedy, Connally's torso, his wrist, and then stuck in his leg, causing a total of four wounds. Some confusion as to the course of the bullet was caused by an incorrect model of events, which had JFK and Connally sitting at the same height, one directly behind the other. Neither of these were true to the actual event. Careful, painstaking computer modelling by Dale K. Myers (see link below) has proven that both were in such a position that Oswald's bullet passed through almost straight. The bullet took heavy damage in the process, being severely flattened. However, hoaxbuff sites invariably show the least damaged side of the bullet, and pretend the whole bullet was impossibly pristine.

Then came the head shot...

At Zaprogen frames 312-313, his head is clearly knocked down and forward about 3 inches by Oswald's bullet, then his head exploded forward and to the right, twisting him back and to the left, and slumped over onto his wife. The limousine then sped away, rushing the President to Parkland Memorial Hospital where he was pronounced dead. Some observers and researchers mistakenly claim the shots were fired from the front, from the grassy knoll ahead of the motorcade.However, at the instant of the head shot, there was a concrete wall between the alleged Grassy Knoll Gunman position, and the President's head. Also, forensics made it perfectly clear that both shots that hit the President, came from the rear (Oswald's position). Among other things, the bullet left a bevel on the inside rear of the skull, which could not have happened from a shot from the front.

Texas Governor John Connaly, in the limousine with the President, was also shot and wounded. Vice President Lyndon, also in the motorcade, took the oath of office aboard Air Force One while flying back to Washington DC. with the body of the dead President.

Official accounts, and evidence-based historical analysis make it clear that Lee Harvey Oswald was the lone assassin, shooting President Kennedy from the Book Depository Building. To date, there has been no shred of evidence to support the belief that Oswald needed or had help.