To what extent did the Chinese government force Catholic priests to marry?

In his book *The Souls of China*, Ian Johnson writes about a type of religious persecution that was inflicted on some groups in China during the Cultural Revolution (1966–76): > Across the country, Buddhist, Daoist, and Catholic clergy who had taken vows of chastity were forced to marry. ([page 26](https://books.google.com/books?id=E9dLDwAAQBAJ&pg=PA26)) Sadly, Johnson doesn't provide any additional information about this, and a quick Google search didn't give me any clues either. This situation raises a number of related questions. - First of all, do we know approximately how many cases of this type of persecution were inflicted on Catholics? - Second, how did the government put the "marriage" into effect? Who officiated, and was it done in a church? - Third, did the government actually attempt to enforce this "marriage"? Did it require that the "married" people live together? Did it somehow ensure that vows of chastity were broken? - Fourth, would such involuntary "marriages," even if they were performed in accordance with government laws, considered invalid by the Church? I assume so! Put simply, to what extent (both quantitatively and qualitatively) did the Chinese government force Catholic clergy to "marry" during the Cultural Revolution?