and his nephew, the last Grand Master of the Teutonic Knights, Albert of Brandenburg-Ansbach, a member of a cadet branch of the House of Hohenzollern, agreed that the latter would resign his position, adopt Lutheran faith and assume the title of Duke of Prussia. Thereafter referred to as Ducal Prussia (; ), remaining a Polish fief. Thus in a deal partially brokered by Martin Luther, Roman Catholic Teutonic Prussia was transformed into the Duchy of Prussia, the first Protestant state. Sigismund's consent was bound to Albert's submission to Poland, which became known as the Prussian Homage. On 10 December 1525 at their session in Königsberg the Prussian estates established the Lutheran Church in Ducal Prussia by deciding the Church Order. The Habsburg-led Holy Roman Empire continued to hold its claim to Prussia and furnished grand masters of the Teutonic Order, who were merely titular administrators of Prussia, but managed to retain many of the Teutonic holdings elsewhere outside of Prussia. Archaeology Fortifications of the Ordensstaat have been examined through archaeological excavation since the end of World War II, especially those built or expanded during the fourteenth century. Fortifications are generally the best preserved material legacy of the Order's presence in the Baltic today, and timber and earth, as well as brick examples, are attested in the archaeological record. The earliest castles in the Ordensstaat consisted of simple buildings attached to a fortified enclosure and, whilst the quadrangular red-brick structure would come to typify convent buildings, single-wing castles would continue to be built alongside timber towers. Where they followed the conventional layout, castles included a connected set of communal spaces such as a dormitory, refectory, kitchen, chapter house, a chapel or church, an infirmary, and tower projecting over the moat. Marienburg fort Construction began on Marienburg during the third quarter of the thirteenth century, and work continued on it until the middle of the fifteenth century. A settlement developed alongside the castle, which together enclosed 25 hectares. Granted town rights in 1286, its castle is larger than any other built by the Order. Since 1997 the outer bailey has been thoroughly excavated, dating to the mid-1350s. Preserved at Marienburg was a polychrome statue of Mary about eight meters in height, made of artificial stone and originally decorated with mosaic tiles. Mary was the most important patron of the knights and central to the liturgy of the Teutonic Order, so it is