Year of Our Lord 1570
Quo Primum
Published in 1570 after the council of Trent, this writing of Pope Saint Pius V is widely considered to be what cemented the "Tridentine" Liturgy (The Latin Mass) and made it the Mass of All Time!
Year of Our Lord 1963
Sacrosanctum Concilium
Widely considered to be a conserved document when voted on by the Second Vatican Council, this writing was heralded by Archbishop Annibale Bugnini, Chief Secretary of the Council. This was the document that paved the way for the liturgical reforms of the Novus Ordo ("New Mass") and its post-concilliur implementation.
Year of Our Lord 1988
Ecclesia Dei
Written long after the time of the Second Vatican Council, this Motu Propio Letter of Pope Saint John Paul II adressed the episcopal consecrations of the Society of Saint Pius The Tenth (SSPX) but more importantly established the rights of Latin Mass Catholics in a post-Vatican II world.
Year of Our Lord 2007
Summorum Pontificum
In order to facilitate the growing Latin Mass movement following Ecclesia Dei, His Holiness Pope Benedict XVI established celebrating the Latin Mass as a universal right of every Catholic priest. This letter also clarified that the Latin Mass was never "banned" and that it would instead become the Extraordinary Form of the Latin Rite.
Year of Our Lord 2021
Traditionis Custodes
A vast restriction of the Latin Mass, this letter of Pope Francis limited the creation of new Traditional Catholic orders and also left the celebration of the Extraordinary Form of the mass up to each diocese's bishop; a move that led to widespread bans in order to reflect the Holy Father's desire.