Had it not been for the fact that Eisele damaged his shoulder during a zero-G training flight aboard a KC-135 aircraft just before Christmas 1965, he might have been in the senior pilot’s seat aboard Apollo 1, instead of Ed White.
The success of Gus Grissom and John Young’s Gemini 3 flight paved the way for long duration space missions. The longest U.S. manned space flight to date was Gordon Cooper’s 34 hour Mercury flight. The Soviets, however, had four long duration flights to their credit, ranging from 70 to 119 hours. It was time for the US to attempt a long duration flight.