In December 1968, the Soviet Union had its last opportunity to attempt to beat the United States to a manned circumnavigation of the moon. A Proton rocket was readied at Baikonur, and a crew was prepared to perform the mission. However, the Soviet authorities decided against it at the last minute, given the horrible record of test moon circumnavigations with the Proton - 10 of 11 test launches failed or resulted in the death of their biological payloads, and none would have been survivable for humans. That turned out to be a good decision, as when that very rocket was launched, it too was a failure.
However, what if the Soviets had decided to be reckless and attempted the launch?
What would have been the implications of a failure, and especially what would have been the implications of a successful mission, several days before the Americans launched Apollo 8?