The fabled pastor of my home parish, the late Msgr. Richard Schuler told stories about being in Rome when Ven. Pius XII infallibly declared the Assumption of the Blessed Virgin to be a dogma of the Faith. He was present for the procession with the icon of Salus Populi Romani and for the proclamation.
Here is a video about the event in 1950.
And there is this… just after 26:00 you hear Pius reading the actual Proclamation of the Dogma.