April 12, 1961
Yuri Gagarin was in space just slightly less than 1 orbit.
The FAI specifies certain guidelines for spaceflight. It is not necessary that a space agency follow these guidelines, but if that space agency wants to file a claim for a record, or if dispute arises, then the FAI will make sure that the guidelines were followed.
One of the stipulations for spaceflight requires that the pilot should land inside their craft in order for the record to be valid. This requirement was created to prevent pilots from flying crafts that could not be safely land. The FAI did not wanted to encourage pilots to risk their lives for an aviation record.
This rule became a problem for Gagarin because he did not land inside his spacecraft. Soviet engineers had not yet perfected the braking system that would slow the craft sufficiently for a human to survive the impact. Therefore, the cosmonaut was ejected from the craft.
Soviet authorities went to great lengths to conceal this fact, and many times Gagarin had to lie during press conferences.
4 month later Gherman Titov spent a full day in space, but still ejected during recovery, as that was the way of soviet spaceflight.
John Glenn was the first man to orbit and fulfill the FAI's technicality of returning within the craft, but the technicality if overlooked in the historical record.