Vostok 1 was Gagarin's only spaceflight, but he served as the backup crew to Soyuz 1, which ended in a fatal crash, killing his friend and fellow cosmonaut Vladimir Komarov.

On the land behind their house, the family was allowed to build a mud hut measuring approximately 3 by 3 metres (10 by 10 ft), where they spent 21 months until the end of the occupation.

[8] During this period, Yuri became a saboteur, especially after one of the German soldiers, called "the Devil" by the children, tried to hang his younger brother Boris on an apple tree using the boy's scarf.

In retaliation, Yuri sabotaged the soldier's work; he poured soil into the tank batteries gathered to be recharged and randomly mixed the different chemical supplies intended for the task.

[12][13] The rest of the Gagarin family believed the two older children were dead, and Yuri became ill with "grief and hunger";[14] he was also beaten for refusing to work for the German forces and spent the remainder of the war at a hospital as a patient and later as an orderly.

[16] In 1950, aged 16, Gagarin began an apprenticeship as a foundryman at a steel plant in Lyubertsy, near Moscow,[12][13] and enrolled at a local "young workers" school for seventh-grade evening classes.

He graduated from flight school the next day and was posted to the Luostari Air Base, close to the Norwegian border in Murmansk Oblast, for a two-year assignment with the Northern Fleet.

He underwent physical and psychological testing conducted at Central Aviation Scientific-Research Hospital, in Moscow, commanded by Colonel A.S. Usanov, a member of the commission.

The commission also included Colonel Yevgeniy Anatoliyevich Karpov, who later commanded the training centre, Colonel Vladimir Ivanovich Yazdovskiy, the head physician for Gagarin's flight, and Major-General Aleksandr Nikolayevich Babiychuk, a physician flag officer on the Soviet Air Force General Staff to the Commander in Chief of the Air Force.

[29] From a pool of 154 qualified pilots short-listed by their Air Force units, the military physicians chose 29 cosmonaut candidates, of whom 20 were approved by the Credential Committee of the Soviet government.

[40][31] In August 1960, a Soviet Air Force doctor evaluated his personality as follows: Modest; embarrasses when his humour gets a little too racy; high degree of intellectual development evident in Yuriy; fantastic memory; distinguishes himself from his colleagues by his sharp and far-ranging sense of attention to his surroundings; a well-developed imagination; quick reactions; persevering, prepares himself painstakingly for his activities and training exercises, handles celestial mechanics and mathematical formulae with ease as well as excels in higher mathematics; does not feel constrained when he has to defend his point of view if he considers himself right; appears that he understands life better than a lot of his friends.

[32]The Vanguard Six were given the title of pilot-cosmonaut in January 1961[36] and underwent a two-day examination conducted by a special interdepartmental commission led by Lieutenant-General Nikolai Kamanin, the overseer of the Vostok programme.

Gagarin, Nikolayev, Popovich, and Titov all received excellent marks on the first day of testing, in which they were required to describe the various phases of the mission followed by questions from the commission.

Historian Asif Azam Siddiqi writes of the final selection:[41] In the end, at the State Commission meeting on April 8, Kamanin stood up and formally nominated Gagarin as the primary pilot and Titov as his backup.

[54] Gagarin and Soviet officials initially refused to admit that he had not landed with his spacecraft,[55] an omission which became apparent after Titov's flight on Vostok 2 four months later.

Gagarin's spaceflight records were nonetheless certified and reaffirmed by the FAI, which revised its rules, and acknowledged that the crucial steps of the safe launch, orbit, and return of the pilot had been accomplished.

He was escorted in a long motorcade of high-ranking officials through the streets of Moscow to the Kremlin where, in a lavish ceremony, Nikita Khrushchev awarded him the title Hero of the Soviet Union.

[59][63] While in Manchester, despite heavy rain, he refused an umbrella, insisted that the roof of the convertible car he was riding in remain open, and stood so the cheering crowds could see him.

[83][85] Following his rise to fame, at a Black Sea resort in September 1961, he was reportedly caught by his wife during a liaison with a nurse who had aided him after a boating incident.

The report states that an air-traffic controller provided Gagarin with outdated weather information and that by the time of his flight, conditions had deteriorated significantly.

[93] A similar theory, published in Air & Space/Smithsonian magazine, is that the crew detected the open vent and followed procedure by executing a rapid dive to a lower altitude.

[98] Alexei Leonov, who was also a member of a state commission established to investigate Gagarin's death, was conducting parachute training sessions that day and heard "two loud booms in the distance".

He believes that a Sukhoi Su-15 was flying below its minimum altitude and, "without realizing it because of the terrible weather conditions, he passed within 10 or 20 meters (33 or 66 ft) of Yuri and Seregin's plane while breaking the sound barrier".

[101] On 15 April, the Soviet Academy of Sciences awarded him with the Konstantin Tsiolkovsky Gold Medal, named after the Russian pioneer of space aeronautics.

[24] On the eighth anniversary of the beginning of the Cuban Revolution (26 July), President Osvaldo Dorticos of Cuba presented him with the first Order of Playa Girón, a newly created medal.

During the American space programme's Apollo 11 mission in 1969, astronauts Neil Armstrong and Buzz Aldrin left a memorial satchel containing medals commemorating Gagarin and Komarov on the Moon's surface.

[138] There are statues of Gagarin and monuments to him located in the town named after him as well as in Orenburg, Cheboksary, Irkutsk, Izhevsk, Komsomolsk-on-Amur, and Yoshkar-Ola in Russia, as well as in Nicosia, Cyprus, Druzhkivka, Ukraine, Karaganda, Kazakhstan, and Tiraspol, Moldova.

Houston Mayor Annise Parker, NASA Administrator Charles Bolden, and Russian Ambassador Sergey Kislyak were present for the dedication.

A documentary film titled First Orbit was shot from the International Space Station, combining sound recordings from the original flight with footage of the route taken by Gagarin.

[154] The Russian, American, and Italian crew of Expedition 27 aboard the ISS sent a special video message to wish the people of the world a "Happy Yuri's Night", wearing shirts with an image of Gagarin.