they were engaged in the Great Turkish War, the largest offensive ever by the Ottomans against the Empire's eastern border. With Louis secretly funding the Ottoman assault, Strasbourg was occupied on 30 September 1681 and officially became part of France, although it retained a degree of economic and political autonomy until 1726. Marshal Boufflers simultaneously laid siege to Luxembourg but Louis now decided it was impolitic for him to attack another Christian kingdom while under attack from the infidel Turk and in March 1682 Boufflers withdrew his troops. However, on 12 September 1683 a combined Imperial, German and Polish army defeated the Ottomans at the Battle of Vienna and forced them to retreat. War After halting the Ottoman advance at Vienna, the Habsburgs were able to turn their attentions to the west. Spain declared war on France on 26 October 1683 and on the night of 3–4 November, an army under the Humières entered the Spanish Netherlands and surrounded Courtrai. After it surrendered on 6 November, he then advanced on Diksmuide, which surrendered without a fight on 10th. Between 22 to 26 December, a second force under Marshal François de Créquy bombarded Luxembourg with 3,000 to 4,000 mortar shells but with winter approaching and the city refusing to yield, he withdrew. Louis renewed the siege of Luxembourg in April 1684, assisted by his technical expert on siege warfare, Sébastien le Prestre de Vauban. Its 2,500 defenders surrendered on 3 June, although fighting continued elsewhere until the Truce of Ratisbon on 15 August 1684. France retained territory taken during the war, including Strasbourg and Luxembourg and subsequent actions were intended to make the truce permanent. Despite its limited scope and length, the conflict is remembered as an especially bloody conflict, since Louis XIV deliberately employed violence as state policy, with the aim of pressuring enemy officials to surrender. Louvois ordered Montal to burn 20 villages near Charleroi because the Spanish previously destroyed two barns on the outskirts of two French villages, and insisted not a single house should remain standing in the 20 villages. A separate but related conflict took place in the Republic of Genoa, whose bankers and financial houses such as the Centurioni, Palavicini and Vivaldi families had long-standing relationships with Spain, and had been lending money to the Spanish government since the 16th century. During the recent war, they allowed the Spanish to recruit mercenaries from Genoese territory