Rorate Caeli

1962 Missal at 50
Saint Joseph is added to the Canon: the last major change to the Traditional Mass as we know it

A threshold previous pontiffs had not dared cross: but Pope John XXIII (born Angelo Giuseppe - Joseph - Roncalli) did, and, weeks into the first session of the Second Vatican Council, the last major change in the history of the Missale Romanum as we know it took place when a decree of the Sacred Congregation of Rites, promulgated exactly 50 years ago, on November 13, 1962, added the phrase "and also of the blessed Joseph, Spouse of the same Virgin" to the text of the Communicantes, in the beginning of the Canon Missae. 

The text of the Missal, adapted to the 1960 rubrics, had been made available just a few months earlier. The change went into effect on the feast of the Immaculate Conception, December 8, 1962.