Excerpts from Books and Wikipedia
"The Civil Constitution of the Clergy (1790), a misconceived attempt to destroy, not the Church, but the Roman absolutist allegiance of the Church, drove the majority of the clergy and of their faithful into opposition, and helped to drive the king into the desperate, and as proved suicidal, attempt to flee the country." [Hobsbawm: Revolution, p. 64]
"The Civil Constitution of the Clergy (French: "Constitution civile du clergé") was a law passed on 12 July 1790 during the French Revolution, that caused the immediate subordination of the Catholic Church in France to the French government.
Earlier legislation had already arranged the confiscation of the Catholic Church's French land holdings and banned monastic vows. This new law completed the destruction of the monastic orders, outlawing "all regular and secular chapters for either sex, abbacies and priorships, both regular and in commendam, for either sex", etc." [Wikipedia]