Question: When did the place where Mater et Magistra's author died become its own country?

Knowledge 1: Mater et magistra
Mater et magistra is the encyclical written by Pope John XXIII on the topic of "Christianity and Social Progress". It was promulgated on 15 May 1961. The title means "mother and teacher", referring to the role of the church. It describes a necessity to work towards authentic community in order to promote human dignity. It taught that the state must sometimes intervene in matters of health care, education, and housing. [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: 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: Mater et magistra
Mater et magistra is the encyclical written by Pope John XXIII on the topic of "Christianity and Social Progress". It was promulgated on 15 May 1961. The title means "mother and teacher", referring to the role of the church. It describes a necessity to work towards authentic community in order to promote human dignity. It taught that the state must sometimes intervene in matters of health care, education, and housing.
Knowledge 1: Mater et magistra
Mater et magistra is the encyclical written by Pope John XXIII on the topic of "Christianity and Social Progress". It was promulgated on 15 May 1961. The title means "mother and teacher", referring to the role of the church. It describes a necessity to work towards authentic community in order to promote human dignity. It taught that the state must sometimes intervene in matters of health care, education, and housing. [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: Lino Grech
Lino Grech died on the night of 1 December 2013, aged 83, at the Mater Dei Hospital in Msida. His funeral mass took place in his hometown of Sliema on 4 December. He was survived by his wife, Frances, and their children.

Answer: 11 February 1929