The Archdiocese of Turku (Turun arkkihiippakunta, Åbo ärkestift), historically known as Archdiocese of Åbo, is the seat of the Archbishop of Turku. It is a part of the Evangelical Lutheran Church of Finland, and its see city is Turku. The Archbishop has many administrative tasks relating to the National church, and is the Metropolitan and Primate of the church. In common with other Lutheran and Anglican churches the Archbishop is considered primus inter pares while all diocesan bishops retain their independence within their respective jurisdictions. This also applies to the Bishop of Turku Archdiocese. The Archdiocese of Turku has a unique episcopal structure as there are two bishops in the Diocese. Influenced by papal bulls, Swedish magnates in the 12th century set up crusading expeditions to convert the heathens in the eastern Baltic. This resulted in the establishment of the Catholic Church, the Christian religion and the Swedish conquest of southern Finland in 1249. Turku, or Åbo, became the principal city in Finland and residence of a Bishopric (the Bishopric of Turku; or episcopus Aboensis). As a result of Protestant Reformation in the 16th century the Catholic Church had to give way for the Lutheran state church that was established by King Gustav Vasa of Sweden. The principal ecclesiastical reformer in Finland was Mikael Agricola who from 1554 onward was also the Bishop of the Turku Diocese. After the Finnish War in 1809, Finland became a part of the Russian Empire as an autonomous Grand Duchy. In 1817 the Bishop was elevated in the status of Archbishop and thus became the head of the Church in Finland. The Lutheran Church thereby became the state church of the Grand Duchy. In 1870, the church was detached from the state as a separate judicial entity. After Finland had gained independence in 1917, through the constitution of 1919 and the act on religious freedom of 1922 the Evangelical Lutheran Church of Finland became a national church of Finland (along with the Finnish Orthodox Church, which however did not get a constitutional position).