What was the name of the militant youth movement in China during the Cultural Revolution?

The Red Guards were a student mass paramilitary social movement mobilized by Mao Zedong in 1966 and 1967, during the Cultural Revolution.

The first students to call themselves "Red Guards" in China were a group of students at the Tsinghua University Middle School who were given the name Red Guards to sign two big-character posters issued on 25 May – 2 June 1966. The students believed that the criticism of the play Hai Rui Dismissed from Office was a political issue and needed greater attention. The group of students, led by Zhang Chengzhi at Tsinghua University Middle School and Nie Yuanzi at Peking University, originally wrote the posters as a constructive criticism of Tsinghua University and Peking University's administration, who were accused of harboring intellectual elitism and bourgeois tendencies.

The Red Guards were denounced as counter-revolutionaries and radicals by the school administration and fellow students, and were forced to secretly meet amongst the ruins of the Old Summer Palace. Nevertheless, Chairman Mao Zedong ordered that the manifesto of the Red Guards be broadcast on national radio and published in the People's Daily newspaper. This action gave the Red Guards political legitimacy, and student groups quickly began to appear across China.