===Union of Brest (1596)===
===Orientalium Ecclesiarum (Vatican II)===
Orientalium Ecclesiarium, the Decree on the Eastern Catholic Churches, was promulgated at the Second Vatican Council by Pope Paul VI on November 21, 1964. This decree instructs Eastern Catholics to "preserve their legitimate liturgical rite" and was in many ways a move away from previous episodes of open Latinizations. The Eastern liturgical traditions, at this time often heavily Latinized, was affirmed by the Council. In situations where the Eastern Tradition was lost, it was to be reclaimed. An example of this is the practice of infant Chrismation and communion and the singing of the Divine Office (i.e. Vespers and Matins) which, largely lost in many Eastern Catholic Churches, was slowly reclaimed after the council.