Question: When did the city where the author of Sacerdotii Nostri Primordia died become its own country?

Knowledge 1: Canonization of Pope John XXIII and Pope John Paul II
Pope John XXIII (25 November 1881 – 3 June 1963) and Pope John Paul II (18 May 1920 – 2 April 2005) reigned as popes of the Roman Catholic Church and the sovereigns of Vatican City (respectively from 1958 to 1963 and 1978 to 2005). Their canonizations were held on 27 April 2014. The decision to canonize was made official by Pope Francis on 5 July 2013 following the recognition of a miracle attributed to the intercession of John Paul II, while John XXIII was canonized for his merits of opening the Second Vatican Council. The date of the canonization was assigned on 30 September 2013. [SEP] Knowledge 2: Vatican City
The name Vatican city was first used in the Lateran Treaty, signed on 11 February 1929, which established the modern city - state. The name is taken from Vatican Hill, the geographic location of the state. ``Vatican ''is derived from the name of an Etruscan settlement, Vatica or Vaticum meaning garden, located in the general area the Romans called vaticanus ager,`` Vatican territory''. [SEP] Knowledge 3: Sacerdotii nostri primordia
Sacerdotii nostri primordia ("From the beginning of our priesthood") was the second encyclical of Pope John XXIII, issued 1 August 1959. It commemorated the 100th anniversary of the death of St. John Vianney, the patron saint of priests.
Knowledge 1: Sacerdotii nostri primordia
Sacerdotii nostri primordia ("From the beginning of our priesthood") was the second encyclical of Pope John XXIII, issued 1 August 1959. It commemorated the 100th anniversary of the death of St. John Vianney, the patron saint of priests. [SEP] Knowledge 2: Canonization of Pope John XXIII and Pope John Paul II
Pope John XXIII (25 November 1881 – 3 June 1963) and Pope John Paul II (18 May 1920 – 2 April 2005) reigned as popes of the Roman Catholic Church and the sovereigns of Vatican City (respectively from 1958 to 1963 and 1978 to 2005). Their canonizations were held on 27 April 2014. The decision to canonize was made official by Pope Francis on 5 July 2013 following the recognition of a miracle attributed to the intercession of John Paul II, while John XXIII was canonized for his merits of opening the Second Vatican Council. The date of the canonization was assigned on 30 September 2013. [SEP] Knowledge 3: Vatican City
The name Vatican city was first used in the Lateran Treaty, signed on 11 February 1929, which established the modern city - state. The name is taken from Vatican Hill, the geographic location of the state. ``Vatican ''is derived from the name of an Etruscan settlement, Vatica or Vaticum meaning garden, located in the general area the Romans called vaticanus ager,`` Vatican territory''.
Knowledge 1: Canonization of Pope John XXIII and Pope John Paul II
Pope John XXIII (25 November 1881 – 3 June 1963) and Pope John Paul II (18 May 1920 – 2 April 2005) reigned as popes of the Roman Catholic Church and the sovereigns of Vatican City (respectively from 1958 to 1963 and 1978 to 2005). Their canonizations were held on 27 April 2014. The decision to canonize was made official by Pope Francis on 5 July 2013 following the recognition of a miracle attributed to the intercession of John Paul II, while John XXIII was canonized for his merits of opening the Second Vatican Council. The date of the canonization was assigned on 30 September 2013. [SEP] Knowledge 2: The Turn of the Screw
On Christmas Eve, an unnamed narrator listens to Douglas, a friend, read a manuscript written by a former governess whom Douglas claims to have known and who is now dead. The manuscript tells the story of how the young governess is hired by a man who has become responsible for his young nephew and niece after the deaths of their parents. He lives mainly in London but also has a country house, Bly. He is uninterested in raising the children. [SEP] Knowledge 3: Sacerdotii nostri primordia
Sacerdotii nostri primordia ("From the beginning of our priesthood") was the second encyclical of Pope John XXIII, issued 1 August 1959. It commemorated the 100th anniversary of the death of St. John Vianney, the patron saint of priests.

Answer: 11 February 1929