The above poster, titled "Tempering Red Hearts in Stormy Waves," was produced in 1972 by four graduates from one of China's top art academies, the Zhejiang Art Academy (now the China Academy of Art): Dong Xiaoming, Zong Wenlong, Gao Eryi, and Liang Pingbo. The boy standing proudly in the center of the photo looks to be a member of the Little Red Guards, a youth group established during the Cultural Revolution.
This poster, from 1971, commemorates the 100th anniversary of the Paris Commune, during which a worker's movement took power in Paris for two months and attempted to institute socialism.
"Iron Bastion: Joint Defense by the Army and the People," from 1974, shows a civilian alongside an army leader defending the Chinese border -- from what, it's unclear, as China has faced no major invasions since World War II. The point, again, is to drive home the solidarity between soldier and worker.