[1] Notable relatives include cousin Chinese Premier Yan Huiqing, in-law Liu Hongsheng, and the Soong sisters.
Yen actively treated patients during the Japanese occupation of China in World War II, and subsequently during the Cultural Revolution.
Due to his historical, social status, practice of Christianity, and Western ties, he was barred from joining the Chinese Communist Party (CCP).
[2] Both his father and his uncle, Yen Yongjing, had volunteered to fight for the Union North in the American Civil War while attending college at Kenyon in Ohio.
[4] After the Anglo-Boer War in South Africa, the British government sought to address the issue of a labor shortage and subsequent low production in Witwatersrand gold mines with workers imported from China.
He found his own clinical skills to be inadequate, and after practicing in South Africa for one year, Yen went on to the United States to further his medical studies.
Despite the fears of his colleague Dr. Hume that he would give up his work in preventive medicine, Yen simply added Ophthalmology to his medical practice.
[6] While working at the Hunan-Yale Medical College in 1919, Yen received a Director's approval to grant a free sickbed to a peasant woman who had fallen ill after delivering a baby.
Yen's efforts, which included a hygiene program to address cases of snail fever in the Tongting Lake area, and the construction of an advanced sanitation system and public education campaign to address hookworm infestations among coal miners,[6] ultimately laid the foundation for standardizing industrial sanitation rules in China.
The social and political atmosphere that emerged around the time of the May Fourth Movement in 1919 largely shaped China's tumultuous twentieth century.
[7] The anti-imperialist, anti-western, and nationalist student-driven movements and the Northern Expedition led by the Kuomintang had a strong impact on the environment in which foreign-educated professionals like Yen could operate.
[6] Later that year, the Northern Expedition army captured Nanjing and attacked foreign institutions, homes, consulates, churches, and schools.
[6] Despite the danger inherent to both academics and those with foreign ties, Yen led a group from PUMC into Wuhan as part of the Wounded Soldiers Relief Association to treat those who had been injured in the fighting.
[6] In 1929, shortly before departing to participate in the Pan-Pacific Surgery Conference in Honolulu, Yen drew up plans for establishing the Sun Yat-sen Memorial Hospital.
By January 1931, significant funding had been secured from sources such as fellow Yale alumnus, Central Bank President H. H. Kung, Sun Yat-Sen, Chiang Kai-Shek, and the Soong sisters, and the project was officially initiated.
[6] The hospital's mission was to focus on public health and disease prevention, both considered major gaps in healthcare in the city of Shanghai at that time.
On August 23, Japanese soldiers attacked one of several medical auxiliary groups and shot five doctors and nurses on their knees at point blank range.
As both a doctor and in his capacity as Public Health Minister, Yen was concerned with the high rates of disease and dismal living conditions of many citizens, particularly laborers.
After the Japanese war and occupation, these were subsequently converted to full hospitals and served as foundations for the area's public medical infrastructure.
[3] Yen recalled his eldest son William (Woqing) from college in the United States to assist in the war effort.
Yen's wife Cao Xiuying, as a leader of the Shanghai Anti-Japanese Women's Federation, set up an orphanage for wartime orphans.
Yen was accused of living a “decadent and bourgeois life”, for crimes just as listening to foreign music, and answering the telephone with in English.
They destroyed gramophone records of Western classical music and jazz, as well as his family's personal effects, including a granddaughter's dollhouse.
[6] In later searches of Yen's home,the Red Guards gradually removed gold, jewelry, US dollars, deeds to property, a refrigerator, a motorcycle, several bicycles, trunks of clothing and textiles and more.
[6] After much of the family's property had been stolen, the Red Guards would come into the homes and carve their names or CCP slogans into walls and cabinets.
[citation needed] After suffering a sudden pulmonary episode at home, Yen was rushed to the Sun Yatsen Hospital, where he was refused treatment for political reasons.
Yen was able to receive medication and oxygen through a series of illegal channels, including Dr. Li Huade at Sun Yatsen hospital.
His contributions to the foundation of public and western medicine across China were critical to the tremendous economic and social growth that the country has enjoyed since the 1980s.
In one story, she was said to have lent a Steinway piano to an impoverished fellow parishioner in the 1930s in order to help the woman provide for her two young daughters.
[6] During his time at Yale Medical School, Yen became close friends with the only other two foreign students, Jacque Louis Buttner, from France, and Carl Johannes Grade, from Denmark.