During the War of Spanish Succession, most of the territories of the Crown of Aragon, including Catalonia, fiercely supported Archduke Charles, the Habsburg contender, who swore the Catalan constitutions, against the Bourbon contender, who would later abolish the Catalan constitutions and political institutions through the Nueva Planta Decrees. The Habsburgs' English allies withdrew from the war with the Treaty of Utrecht in 1713, and shortly thereafter, Habsburg troops were evacuated from Italy and from Spain. This left the Catalan government isolated, but it remained loyal to Charles. After a 14-month siege, Barcelona surrendered to a Bourbon army on 11 September 1714. The end of the war was followed by the loss of the "fueros" of all Crown of Aragon territories, including Catalonia, and the imposition of the Nueva Planta decrees, which centralised Spanish government. 11 September, the date of the fall of Barcelona, was commemorated by Catalan nationalists from 1886, and in the 20th century it was chosen as the National Day of Catalonia.