Ubi Primum and Deiparae Virginis Mariae are a unique set Encyclical since it isn’t a typical Encyclical but in it the Pope asking the bishops of the world along with all the clergy and lay people if it is wise and prudent that the Immaculate Conception and the Assumption should become Dogma. It is pretty cool to see some “working documents” on these points of dogma.
In Ubi Primum Pius IX in 1849 writes to the bishops of the increase of Marian devotion both public and privately took place during Pope Gregory XVI’s reign (Pope before Pius). Gregory’s reign was also a time when people began pressing for a definition of Immaculate Mary. Yet the entirety of the Encyclical is asking if the Immaculate Conception should be made dogma.
In Deiparae Virginis Mariae Pius XII in 1946 almost 100 year later begins that there have been calls about making the Assumption dogma for about the same amount of time, Pius notes that there are several petitions from 1849-1940 have been compiled in a two volume and these came from just about everyone. So in the steps of Pius IX he thought to ask if the Assumption should be made dogma