3D postcard showing the Soyuz I spacecraft.
Soyuz I was a manned spaceflight in 1967 carrying astronaut Vladimir Komarov. The flight was plagued with technical issues, and Komarov was killed when the descent module crashed into the ground due to a parachute failure. This was the first in-flight fatality in the history of spaceflight.
Yuri Gagarin was the backup pilot for Soyuz 1, and was aware of the design problems and the pressures from the Politburo to proceed with the flight. He attempted to “bump” Komarov from the mission, knowing that the Soviet leadership would not risk a national hero on the flight. At the same time, Komarov refused to pass on the mission, even though he believed it to be doomed. He explained that he could not risk Gagarin’s life.