Twenty cosmonaut candidates were selected from an initial pool of almost 3,500 military pilots, beginning training in spring 1960.
Notes on verification
Twenty selected and spring 1960 training start are well corroborated by multiple independent sources. The 'almost 3,500' initial pool figure is not independently confirmed elsewhere; other sources cite varying numbers (154, 206, ~3,000) likely reflecting different funnel stages.
Sources
- How Yuri Gagarin Was Picked to Be First in Space (smithsonianmag.com)
- https://www.amazon.com/First-Soviet-Cosmonaut-Team-Legacies/dp/0387848231 (amazon.com)
- https://nasa.gov/history/60-years-ago-soviets-select-their-first-cosmonauts (nasa.gov)
- https://www.russiamatters.org/analysis/declassified-sources-gagarin (russiamatters.org)